Ubuntu 18.04, I get about a dozen or so of these a day:

Jul 17 21:58:29 [servername] NetworkManager[929]: <info> [1626577109.7049] connectivity: (enp3s0) timed out

I was getting these on the built-in NIC on the motherboard, so I replaced that with a daughter-card NIC, and disabled the onboard NIC, but I am still getting the same problem. I have replaced the network cable, still no joy. Router is essentially brand new. Any thoughts?

@Terrance:

> lspci | grep Ethernet
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (7) I219-V (rev 10)
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 07)
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. Device 8161 (rev 15)

> lshw -C network | grep configuration
configuration: autonegotiation=on broadcast=yes driver=r8169 duplex=full firmware=rtl8168e-3_0.0.4 03/27/12 ip=10.1.1.182 latency=0 link=yes multicast=yes port=MII speed=100Mbit/s
configuration: autonegotiation=on broadcast=yes driver=r8169 duplex=full firmware=rtl8168h-2_0.0.2 02/26/15 ip=192.168.1.120 latency=0 link=yes multicast=yes port=MII speed=1Gbit/s
configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=3.2.6-k firmware=0.2-4 latency=0 link=no multicast=yes port=twisted pair

> ifconfig
enp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.1.1.182  netmask 255.255.255.0  broadcast 10.1.1.255
        inet6 fe80::1efd:8ff:fe70:2173  prefixlen 64  scopeid 0x20<link>
        ether 1c:fd:08:70:21:73  txqueuelen 1000  (Ethernet)
        RX packets 222302237  bytes 320974231227 (320.9 GB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 98557310  bytes 6537060870 (6.5 GB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.120  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::a27a:416f:4a38:f590  prefixlen 64  scopeid 0x20<link>
        ether 00:31:92:46:96:a5  txqueuelen 1000  (Ethernet)
        RX packets 81523790  bytes 87489473670 (87.4 GB)
        RX errors 0  dropped 12  overruns 0  frame 0
        TX packets 82257248  bytes 88740819287 (88.7 GB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 10158  bytes 1314073 (1.3 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 10158  bytes 1314073 (1.3 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enp3s0 is the one giving me problems. enp2s0 almost never gives a timeout. The original onboard NIC is now disabled, so it doesnt seem to show in ifconfig.

@heynnema

> lshw -C network
  *-network
       description: Ethernet interface
       product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:02:00.0
       logical name: enp2s0
       version: 07
       serial: 1c:fd:08:70:21:73
       size: 100Mbit/s
       capacity: 1Gbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8169 duplex=full firmware=rtl8168e-3_0.0.4 03/27/12 ip=10.1.1.182 latency=0 link=yes multicast=yes port=MII speed=100Mbit/s
       resources: irq:17 ioport:4000(size=256) memory:a2200000-a2200fff memory:a0000000-a0003fff
  *-network
       description: Ethernet interface
       product: Realtek Semiconductor Co., Ltd.
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:03:00.0
       logical name: enp3s0
       version: 15
       serial: 00:31:92:46:96:a5
       size: 1Gbit/s
       capacity: 1Gbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8169 duplex=full firmware=rtl8168h-2_0.0.2 02/26/15 ip=192.168.1.120 latency=0 link=yes multicast=yes port=MII speed=1Gbit/s
       resources: irq:18 ioport:3000(size=256) memory:a2104000-a2104fff memory:a2100000-a2103fff
  *-network DISABLED
       description: Ethernet interface
       product: Ethernet Connection (7) I219-V
       vendor: Intel Corporation
       physical id: 1f.6
       bus info: pci@0000:00:1f.6
       logical name: eno1
       version: 10
       serial: 2c:f0:5d:98:b6:ee
       capacity: 1Gbit/s
       width: 32 bits
       clock: 33MHz
       capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=3.2.6-k firmware=0.2-4 latency=0 link=no multicast=yes port=twisted pair
       resources: irq:126 memory:a2300000-a231ffff

@heynnema "Do you currently have 3 ethernet ports... one on-board and two PCI?" Correct. "How did you disable the on-board port?" ifconfig eno1 disable "Why is enp2s0 only running at 100Mb?" Uhm... I dont know, that may be an important part of the puzzle. Its got a new cable, and I have switched it out with another new cable and it made no difference. The router is a Linksys WRT3200ACM.