MTU on Physical Interface not Taking

[dontek]

I'm having an interesting issue I have not seen before, and I have not been able to find a similar situation by searching.

On my core NIC on one of my PVE nodes (9.0.10) the MTU setting will not take. I set 9000; I get 1500.



ip a output:

2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master brmgmt state UP group default qlen 1000
    link/ether d0:50:99:db:88:61 brd ff:ff:ff:ff:ff:ff
    altname enp66s0f0
    altname enxd05099db8861

If I manually edit /etc/network/interfaces and change the device id from enp66s0f0 to eno1, then MTU 9000 sticks, however, then I have a rogue eno1 device in the web UI Networking for the node alongside the enp66s0f0 entry, and any vlans/bridges mapped to enp66s0f0 break. When things are working, less the MTU being 9000 like I want it, vlans using enp66s0f0 as their raw device also get MTU 1500, despite also being set to MTU 9000 in the web GUI.

If it matters, the NIC in question is a dual-port onboard Intel X550 on an ASRock Rack ROMED8-2T motherboard.

If there are some logs I can include to help, please let me know where to look.

Any ideas on how to troubleshoot this? I'm not having this issue with my other nodes, however, they are on different hardware.

 

[dontek]

I should add, I can successfully set MTU to the desired 9000 by command:

ip link set dev enp66s0f0 mtu 9000

However, this does not survive a reboot. Nor does it survive:

ifreload -a

The entry in /etc/network/interfaces for this device is simply:

iface enp66s0f0 inet manual
        mtu 9000
#core

...and the corresponding bridge:

auto brmgmt
iface brmgmt inet static
        address 172.16.0.6/24
        gateway 172.16.0.1
        bridge-ports enp66s0f0
        bridge-stp off
        bridge-fd 0
        mtu 9000
#management

 

[shanreich]

Any errors in the journal? (journalctl -b) - what does the debug output of ifreload say? (ifreload -avd)