I manage three Ubuntu servers running latest LTS, all up 2 date.

The two first are behind a fast fiber networks, with a bridge interface (for containers) Both have an OPNsense router running in libvirt using a dedicated interface via PCI passthrough

The third is hosted by my ISP on a fast network, also with a bridge interface for containers.

ALL THREE servers upload speed is topping at 3 to 4 Mbit/s only! The OPNsense routers can upload at full speed. If I plug a device directly on the modem (WAN), I get the full speed too.

So I suspect that it is related to the network bridges.

Server 1:

/etc/network/interfaces

auto br0
    iface br0 inet static
        address 10.0.4.4
            netmask 255.255.254.0
            network 10.0.4.0
            broadcast 10.0.5.255
            # gateway 10.0.4.1
            dns-nameserver 10.0.4.1
        bridge_ports enp3s0
            bridge_stp on
            bridge_maxwait 0

Interface speed

# ethtool enp3s0 | grep Speed
        Speed: 1000Mb/s

ip a

# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br0 state UP group default qlen 1000
    link/ether 60:a4:4c:cb:4f:5d brd ff:ff:ff:ff:ff:ff
    inet6 fe80::62a4:4cff:fecb:4f5d/64 scope link 
       valid_lft forever preferred_lft forever
4: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 0a:91:86:76:2e:08 brd ff:ff:ff:ff:ff:ff
    inet 10.0.4.4/23 brd 10.0.5.255 scope global br0
       valid_lft forever preferred_lft forever
    inet6 fe80::891:86ff:fe76:2e08/64 scope link 
       valid_lft forever preferred_lft forever

Server 2:

/etc/netplan/01-netcfg.yaml

 bridges:
    br0:
      dhcp4: no
      dhcp6: no
      addresses:
        - 10.0.14.2/24
      gateway4: 10.0.14.1
      nameservers:
        addresses: 
        - 10.0.14.6
      interfaces:
        - eno1

Interface speed

# ethtool eno1 | grep Speed
        Speed: 1000Mb/s

Server 3:

/etc/netplan/01-netcfg.yaml

network:
    ethernets:
        eno1:
            dhcp4: false
            dhcp6: false
        eno2:
            dhcp4: false
            dhcp6: false
            optional: true
        enp0s20f0u1u6:
            dhcp4: true
            dhcp6: false
            optional: true
    bridges:
        br0:
            dhcp4: false
            dhcp6: false
            addresses:
            - [redacted]/24
            - [redacted]/64
            gateway4: [redacted]
            gateway6: [redacted]
            nameservers:
                addresses: 
                - 1.1.1.1
                - 1.0.0.1
                - 8.8.8.8
                - 8.8.8.4
                - 2606:4700:4700::1111
                - 2606:4700:4700::1001
                - 2001:4860:4860::8888
                - 2001:4860:4860::8844
            interfaces:
                - eno1
            parameters:
                stp: false
                forward-delay: 0
    version: 2

Interface speed

# ethtool eno1 | grep Speed
        Speed: 1000Mb/s

Typical servers speed tests:

Ping: 2.987 ms
Download: 279.34 Mbit/s
Upload: 4.10 Mbit/s

Speedtest from a computer plugged into the fiber router OR behind the OPNsense routers

Ping: 2.939 ms
Download: 283.25 Mbit/s
Upload: 180.77 Mbit/s

What I am doing wrong ?