Martin Herrmann's questions

I have an old piece of software, which however works perfectly until now. It is a service, set up with

sudo update-rc.d zcam_101 defaults
sudo service zcam_101 start

Last day I had to change a piece of this and removed the service. I don't know what I did wrong, but when I tried to start the service with update-rc.d again, I get the following very strange error:

Job for zcam_101.service failed because the control process exited with error code. See "systemctl status zcam_102.service" and "journalctl -xe" for details.

This is very strange, it seems that Ubuntu created a systemd service and tries to start this, which can't work, because its an upstart-rc.d software.

I tried to delete the service from systemd, but it seems to hold a reference to the service somewhere I can't find. So I tried the following:

systemctl stop zcam_101
systemctl disable zcam_101
rm /etc/systemd/system/zcam_101
rm /etc/systemd/system/zcam_101
systemctl daemon-reload
systemctl reset-failed

I searched for every file containing zcam beginning in root directory, and got en empty list. I can then install the script with update-rc.d, but as I try to start it, I get the quoted error. Does anybody know how to make Ubuntu handling this script as upstart job or how to completely remove any reference to a never existing zcam_101.service? Or does anybody know how I could run into this problem? Thank you very much.

Edit1: I just found out that there is one file at /run/systemd/generator.late/zcam_101.service which is created by the update-rc.d command. I deleted this one, too, but it does not help.

Edit2: (I mixed up the endings, because I have processes zcam_101 to zcam_104 generated automatically, so don't be confused, if the numbers differ, sorry. I changed all to 101, to not confuse anybody. The problem however occurs with all files.) Output of systemctl cat zcam_101

# /run/systemd/generator.late/zcam_101.service
# Automatically generated by systemd-sysv-generator

[Unit]
Documentation=man:systemd-sysv-generator(8)
SourcePath=/etc/init.d/zcam_101
Description=LSB: SCS ZCam server 101
After=remote-fs.target
After=systemd-journald-dev-log.socket
After=network-online.target
Wants=network-online.target

[Service]
Type=forking
Restart=no
TimeoutSec=5min
IgnoreSIGPIPE=no
KillMode=process
GuessMainPID=no
RemainAfterExit=yes
ExecStart=/etc/init.d/zcam_101 start
ExecStop=/etc/init.d/zcam_101 stop

I have an Ubuntu 16.04 and a debian machine, both connected through a network. On my Ubuntu machine there is service running, which needs to reboot the debian computer when starting the service. The service is invoked by sudo service debian_client start and is doing a bunch of commands like ssh [email protected] reboot on the debian machine. The problem is, I need to type in the password once for every ssh command, which is very annoying.

I tried then to go to ~/.ssh on the Ubuntu machine and did

ssh-keygen -t rsa
ssh-copy-id [email protected]

After that I logged in via ssh [email protected] which works without typing a password. But when invoking the ssh command through the service, I still have to type password. Does anybody know why and how to resolve this issue, I can't find help online for that specific problem?

Interesting part, I changed the script to ssh -v [email protected] and compared the output of the script with the output if I do that via bash. The difference is that the script always looks for keys in /root, like the output shows:

...
debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/id_rsa
debug1: Trying private key: /root/.ssh/id_dsa
debug1: Trying private key: /root/.ssh/id_ecdsa
debug1: Trying private key: /root/.ssh/id_ed25519
debug1: Next authentication method: password

If I do it myself via bash, the output reads:

debug1: Next authentication method: publickey
debug1: Offering RSA public key: user@ubuntucomputer
debug1: Server accepts key: pkalg ssh-rsa blen 279
debug1: Authentication succeeded (publickey).

and I am logged in without any password typed. Can anybody help, why is my service looking for the key at /root/? Thank you very much.

I use a USB Huawei ME906s-158 device as described in Huawei ME906s-158 not working with Ubuntu 16.04. If the module loses the connection it seems to have problems reconnecting to the network. So my idea is to write some script, running in the background checking if the LTE connection is up, and if not release the USB device and reconnect it, using terminal commands. I found helpful information in How to enable/disable mobile broadband from terminal? and on this forum thread, but the code is not running on my Ubuntu 16.04, which may be the problem.

Taking this line for example:

modprobe -r -f uhci_hcd

results in modprobe: FATAL: Module uhci_hcd is builtin. error. The same is true if I use xhci_hcd, which is used for my device. So my question is how to change the modprobe commands to remove/connect my device?

Using dmesg the device is connected as

usb 3-13.1: new high-speed USB device number 117 using xhci_hcd
usb 3-13.1: New USB device found, idVendor=12d1, idProduct=15c1
usb 3-13.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 3-13.1: Product: HUAWEI Mobile
usb 3-13.1: Manufacturer: Huawei Technologies Co., Ltd.
usb 3-13.1: SerialNumber: 0123456789ABCDEF
cdc_ether 3-13.1:2.0 usb0: register 'cdc_ether' at usb-0000:00:14.0-13.1, CDC Ethernet Device, 02:1e:10:1f:00:00

where the device number varies and the usb port depends on the used hardware port. I think I simply don't understand how the device is named or mounted to be addressed with modprobe.

The relevant information of lsusb is Bus 003 Device 028: ID 12d1:15c1 Huawei Technologies Co., Ltd. and lsusb -t delivers

/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/15p, 480M
    |__ Port 12: Dev 11, If 0, Class=Hub, Driver=hub/4p, 480M
        |__ Port 3: Dev 14, If 1, Class=Human Interface Device, Driver=, 1.5M
        |__ Port 3: Dev 14, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 1: Dev 64, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 2: Dev 13, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 2: Dev 13, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M
    |__ Port 13: Dev 3, If 0, Class=Hub, Driver=hub/4p, 480M
    |__ Port 14: Dev 29, If 0, Class=Communications, Driver=cdc_ether, 480M
    |__ Port 14: Dev 29, If 1, Class=CDC Data, Driver=cdc_ether, 480M
    |__ Port 14: Dev 29, If 2, Class=Vendor Specific Class, Driver=option, 480M
    |__ Port 14: Dev 29, If 3, Class=Vendor Specific Class, Driver=option, 480M
    |__ Port 14: Dev 29, If 4, Class=Vendor Specific Class, Driver=option, 480M
    |__ Port 14: Dev 29, If 5, Class=Vendor Specific Class, Driver=option, 480M
    |__ Port 14: Dev 29, If 6, Class=Vendor Specific Class, Driver=option, 480M

Thank you very much for your help.

Here is the full dmesg output:

[748010.825136] usb 3-13.1: new high-speed USB device number 79 using xhci_hcd
[748010.926143] usb 3-13.1: New USB device found, idVendor=12d1, idProduct=15c1
[748010.926146] usb 3-13.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[748010.926147] usb 3-13.1: Product: HUAWEI Mobile
[748010.926148] usb 3-13.1: Manufacturer: Huawei Technologies Co., Ltd.
[748010.926149] usb 3-13.1: SerialNumber: 0123456789ABCDEF
[748010.929581] cdc_ether 3-13.1:2.0 usb0: register 'cdc_ether' at usb-0000:00:14.0-13.1, CDC Ethernet Device, 02:1e:10:1f:00:00
[748010.930008] option 3-13.1:2.2: GSM modem (1-port) converter detected
[748010.930178] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB0
[748010.930451] option 3-13.1:2.3: GSM modem (1-port) converter detected
[748010.930588] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB1
[748010.930829] option 3-13.1:2.4: GSM modem (1-port) converter detected
[748010.930929] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB2
[748010.931153] option 3-13.1:2.5: GSM modem (1-port) converter detected
[748010.931254] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB3
[748010.931474] option 3-13.1:2.6: GSM modem (1-port) converter detected
[748010.931580] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB4
[748010.959172] cdc_ether 3-13.1:2.0 enp0s20u13u1c2: renamed from usb0
[748010.986087] IPv6: ADDRCONF(NETDEV_UP): enp0s20u13u1c2: link is not ready
[748010.986238] cdc_ether 3-13.1:2.0 enp0s20u13u1c2: kevent 12 may have been dropped
[748010.990538] IPv6: ADDRCONF(NETDEV_UP): enp0s20u13u1c2: link is not ready

The full output of tree /sys/devices/pci0000:00/0000:00:14.0/usb3/3-13/ | grep driver is:

│   │   ├── driver -> ../../../../../../../bus/usb/drivers/cdc_ether
│   │   ├── driver -> ../../../../../../../bus/usb/drivers/cdc_ether
│   │   ├── driver -> ../../../../../../../bus/usb/drivers/option
│   │   │   ├── driver -> ../../../../../../../../bus/usb-serial/drivers/option1
│   │   ├── driver -> ../../../../../../../bus/usb/drivers/option
│   │   │   ├── driver -> ../../../../../../../../bus/usb-serial/drivers/option1
│   │   ├── driver -> ../../../../../../../bus/usb/drivers/option
│   │   │   ├── driver -> ../../../../../../../../bus/usb-serial/drivers/option1
│   │   ├── driver -> ../../../../../../../bus/usb/drivers/option
│   │   │   ├── driver -> ../../../../../../../../bus/usb-serial/drivers/option1
│   │   ├── driver -> ../../../../../../../bus/usb/drivers/option
│   │   │   ├── driver -> ../../../../../../../../bus/usb-serial/drivers/option1
│   ├── driver -> ../../../../../../bus/usb/drivers/usb
│   ├── driver -> ../../../../../../bus/usb/drivers/hub
├── driver -> ../../../../../bus/usb/drivers/usb

I'm working on an HP machine with Ubuntu 16.04 installed and kernel 4.10.0-42-generic #46~16.04.1-Ubuntu. I want to use a Huawei ME906s-158 to connect to a mobile network, which is unfortunately mostly not working.

If I plug in the device, I can sometimes use it as expected with the graphical network manager tool. But after a few minutes (mostly after only a few seconds) the connection suddenly disappears without any error message. The network manager shows the device under wired connections as Ethernet Network and disconnected, and it is grayed-out. Often it is not detected as mobile broadband device at all and is shown as wired connection as described before.

I googled a lot but found no solution, which is why I try to get your help here. Please tell me which information you need to help me, these are things I tried:

i) This is the output of "dmesg" when no connection is established

[10396.949204] usb 3-13.1: new high-speed USB device number 11 using xhci_hcd
[10397.050249] usb 3-13.1: New USB device found, idVendor=12d1, idProduct=15c1
[10397.050253] usb 3-13.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[10397.050255] usb 3-13.1: Product: HUAWEI Mobile
[10397.050256] usb 3-13.1: Manufacturer: Huawei Technologies Co., Ltd.
[10397.050258] usb 3-13.1: SerialNumber: 0123456789ABCDEF
[10397.053658] cdc_ether 3-13.1:2.0 usb0: register 'cdc_ether' at usb-0000:00:14.0-13.1, CDC Ethernet Device, 02:1e:10:1f:00:00
[10397.054034] option 3-13.1:2.2: GSM modem (1-port) converter detected
[10397.054182] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB0
[10397.054423] option 3-13.1:2.3: GSM modem (1-port) converter detected
[10397.054564] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB1
[10397.054772] option 3-13.1:2.4: GSM modem (1-port) converter detected
[10397.054905] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB2
[10397.055098] option 3-13.1:2.5: GSM modem (1-port) converter detected
[10397.055220] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB3
[10397.055427] option 3-13.1:2.6: GSM modem (1-port) converter detected
[10397.055559] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB4
[10397.089063] cdc_ether 3-13.1:2.0 enp0s20u13u1c2: renamed from usb0
[10397.139964] IPv6: ADDRCONF(NETDEV_UP): enp0s20u13u1c2: link is not ready
[10397.140197] cdc_ether 3-13.1:2.0 enp0s20u13u1c2: kevent 12 may have been dropped
[10397.145814] IPv6: ADDRCONF(NETDEV_UP): enp0s20u13u1c2: link is not ready
[10413.066889] usb 3-13.1: USB disconnect, device number 11
[10413.066968] cdc_ether 3-13.1:2.0 enp0s20u13u1c2: unregister 'cdc_ether' usb-0000:00:14.0-13.1, CDC Ethernet Device
[10413.089680] option1 ttyUSB0: GSM modem (1-port) converter now disconnected from ttyUSB0
[10413.089692] option 3-13.1:2.2: device disconnected
[10413.089816] option1 ttyUSB1: GSM modem (1-port) converter now disconnected from ttyUSB1
[10413.089822] option 3-13.1:2.3: device disconnected
[10413.089926] option1 ttyUSB2: GSM modem (1-port) converter now disconnected from ttyUSB2
[10413.089935] option 3-13.1:2.4: device disconnected
[10413.090035] option1 ttyUSB3: GSM modem (1-port) converter now disconnected from ttyUSB3
[10413.090043] option 3-13.1:2.5: device disconnected
[10413.090175] option1 ttyUSB4: GSM modem (1-port) converter now disconnected from ttyUSB4
[10413.090182] option 3-13.1:2.6: device disconnected

Always if the connection could be established for short time, dmesg shows:

[10981.483608] usb 3-13.1: new high-speed USB device number 39 using xhci_hcd
[10981.584906] usb 3-13.1: New USB device found, idVendor=12d1, idProduct=15c1
[10981.584909] usb 3-13.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[10981.584911] usb 3-13.1: Product: HUAWEI Mobile
[10981.584913] usb 3-13.1: Manufacturer: Huawei Technologies Co., Ltd.
[10981.584914] usb 3-13.1: SerialNumber: xxx
[10981.588332] cdc_ether 3-13.1:2.0 usb0: register 'cdc_ether' at usb-0000:00:14.0-13.1, CDC Ethernet Device, 02:1e:10:1f:00:00
[10981.588725] option 3-13.1:2.2: GSM modem (1-port) converter detected
[10981.588837] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB0
[10981.589089] option 3-13.1:2.3: GSM modem (1-port) converter detected
[10981.589202] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB1
[10981.589417] option 3-13.1:2.4: GSM modem (1-port) converter detected
[10981.589505] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB2
[10981.589703] option 3-13.1:2.5: GSM modem (1-port) converter detected
[10981.589784] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB3
[10981.589992] option 3-13.1:2.6: GSM modem (1-port) converter detected
[10981.590075] usb 3-13.1: GSM modem (1-port) converter now attached to ttyUSB4
[10981.632588] cdc_ether 3-13.1:2.0 enp0s20u13u1c2: renamed from usb0
[10981.675707] IPv6: ADDRCONF(NETDEV_UP): enp0s20u13u1c2: link is not ready
[10981.675926] cdc_ether 3-13.1:2.0 enp0s20u13u1c2: kevent 12 may have been dropped
[10981.680673] IPv6: ADDRCONF(NETDEV_UP): enp0s20u13u1c2: link is not ready
[11012.270567] IPv6: ADDRCONF(NETDEV_CHANGE): enp0s20u13u1c2: link becomes ready
[11012.270577] cdc_ether 3-13.1:2.0 enp0s20u13u1c2: kevent 12 may have been dropped
[11012.275779] cdc_ether 3-13.1:2.0 enp0s20u13u1c2: kevent 12 may have been dropped

ii) "lsusb -v" shows:

Bus 003 Device 018: ID 12d1:15c1 Huawei Technologies Co., Ltd. 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.10
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol       255 
  bMaxPacketSize0        64
  idVendor           0x12d1 Huawei Technologies Co., Ltd.
  idProduct          0x15c1 
  bcdDevice            1.02
  iManufacturer           1 Huawei Technologies Co., Ltd.
  iProduct                2 HUAWEI Mobile
  iSerial                 3 xxx
  bNumConfigurations      3
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength          301
    bNumInterfaces          6
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xa0
      (Bus Powered)
      Remote Wakeup
    MaxPower                2mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           3
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      6 
      bInterfaceProtocol     16 
      iInterface              7 Huawei Mobile Connect - Modem
      ** UNRECOGNIZED:  05 24 00 10 01
      ** UNRECOGNIZED:  04 24 02 02
      ** UNRECOGNIZED:  05 24 01 00 00
      ** UNRECOGNIZED:  05 24 06 00 00
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x000a  1x 10 bytes
        bInterval               9
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      6 
      bInterfaceProtocol     19 
      iInterface              8 Huawei Mobile Connect - Application
      ** UNRECOGNIZED:  05 24 00 10 01
      ** UNRECOGNIZED:  04 24 02 02
      ** UNRECOGNIZED:  05 24 01 00 01
      ** UNRECOGNIZED:  05 24 06 00 00
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
    ... (do you need the full information, it has more than max. allowed characters?)

iii) "usb-devices" shows:

T:  Bus=03 Lev=01 Prnt=01 Port=08 Cnt=03 Dev#= 44 Spd=480 MxCh= 0
D:  Ver= 2.10 Cls=00(>ifc ) Sub=00 Prot=ff MxPS=64 #Cfgs=  3
P:  Vendor=12d1 ProdID=15c1 Rev=01.02
S:  Manufacturer=Huawei Technologies Co., Ltd.
S:  Product=HUAWEI Mobile
S:  SerialNumber=xxx
C:  #Ifs= 7 Cfg#= 2 Atr=a0 MxPwr=2mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=02(commc) Sub=06 Prot=00 Driver=cdc_ether
I:  If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=06 Prot=00 Driver=cdc_ether
I:  If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=06 Prot=10 Driver=option
I:  If#= 3 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=06 Prot=13 Driver=option
I:  If#= 4 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=06 Prot=12 Driver=option
I:  If#= 5 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=06 Prot=14 Driver=option
I:  If#= 6 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=06 Prot=1b Driver=option

Interestingly the device is sometimes not listed in usb-devices and lsusb.

iv) "mmcli -L" shows

No modems were found

or if a connection is possible:

Found 1 modems:
    /org/freedesktop/ModemManager1/Modem/16 [Huawei Technologies Co., Ltd.] ME906s-158

If a modem is detected I can use "sudo mmcli -m xx" (here xx=16), showing:

/org/freedesktop/ModemManager1/Modem/17 (device id '8f2c1ff8885e6c1f5b123a3b7382aa49353c683c')
  -------------------------
  Hardware |   manufacturer: 'Huawei Technologies Co., Ltd.'
           |          model: 'ME906s-158'
           |       revision: '11.617.04.00.00'
           |      supported: 'gsm-umts'
           |        current: 'gsm-umts'
           |   equipment id: '867160025875216'
  -------------------------
  System   |         device: '/sys/devices/pci0000:00/0000:00:14.0/usb3/3-10'
           |        drivers: 'option1, cdc_ether'
           |         plugin: 'Huawei'
           |   primary port: 'ttyUSB0'
           |          ports: 'ttyUSB0 (at), enp0s20u10c2 (net), ttyUSB2 (at), ttyUSB3 (at)'
  -------------------------
  Numbers  |           own : 'unknown'
  -------------------------
  Status   |           lock: 'none'
           | unlock retries: 'sim-pin (3), sim-pin2 (3), sim-puk (10), sim-puk2 (10)'
           |          state: 'connected'
           |    power state: 'on'
           |    access tech: 'lte'
           | signal quality: '48' (recent)
  -------------------------
  Modes    |      supported: 'allowed: 4g; preferred: none
           |                  allowed: 3g; preferred: none
           |                  allowed: 2g; preferred: none
           |                  allowed: 2g, 3g, 4g; preferred: none'
           |        current: 'allowed: 2g, 3g, 4g; preferred: none'
  -------------------------
  Bands    |      supported: 'unknown'
           |        current: 'unknown'
  -------------------------
  IP       |      supported: 'ipv4'
  -------------------------
  3GPP     |           imei: 'xxx'
           |  enabled locks: 'none'
           |    operator id: 'xxx'
           |  operator name: 'xxx xx'
           |   subscription: 'unknown'
           |   registration: 'home'
  -------------------------
  SIM      |           path: '/org/freedesktop/ModemManager1/SIM/10'

  -------------------------
  Bearers  |          paths: '/org/freedesktop/ModemManager1/Bearer/8'

v) The behavior seemed to occur suddenly. I bought these modules about a month ago and tried them to check whether they are defective or OK, and I can't remember that I experienced similar behavior. It then occured yesterday after the cards where stored in my cupboard.

vi) I tried to setup udev rules, as it is recommended in several forums. I installed usb_modeswitch in version

usb_modeswitch: handle USB devices with multiple modes
 * Version 2.5.0 (C) Josua Dietze 2017
 * Based on libusb1/libusbx

and added

ATTR{idVendor}=="12d1", ATTR{idProduct}=="15c1", RUN+="usb_modeswitch -v 0x12d1 -p 0x15c1 -u 3"

to the "40-usb_modeswitch.rules" file in the beginning, but it did not help.

vii) If I try "usb_modeswitch -v 0x12d1 -p 0x15c1 -u 3" in the console it shows:

Look for default devices ...
   product ID matched
Get the current device configuration ...
 Found devices in default mode (1)
Access device 120 on bus 003
Get the current device configuration ...
Current configuration number is 2
Use interface number 0
 with class 2

USB description data (for identification)
-------------------------
Manufacturer: Huawei Technologies Co., Ltd.
     Product: HUAWEI Mobile
  Serial No.: xxx
-------------------------
Change configuration to 3 ...
 Device is busy, try to detach kernel driver
Looking for active driver ...
 OK, driver detached
 Device is busy, try to detach kernel driver
Looking for active driver ...
 No active driver found. Detached before or never attached
 Device is busy, try to detach kernel driver
Looking for active driver ...
 No active driver found. Detached before or never attached
 Device is busy, try to detach kernel driver
Looking for active driver ...
 No active driver found. Detached before or never attached
 Changing the configuration failed (error -6). Try to continue
-> Run lsusb to note any changes. Bye!

viii) I'm not bound to the network-manager, and tried to setup the connections in its files directly, but the same behavior occured. Until now I did not install other software to setup the my connection. Should I give it a try? Can't I do it without installing another tons of libaries?

ix) This strange behavior occurs with three devices of the same type and three SIM-cards, also of the same type and provider. I also tried to get the modem working on two more computers, one (near) fresh Ubuntu 16.04 installation and one Ubuntu 17 installation. The behavior is the same on both. Until now I did not test with SIM cards of other providers, I will try to do so as soon as possible.

Is there anybody who can help or knows the problem? Thank you very much for your help. Martin