Hey is it possible to somehow achieve that the Guest uses a MTU of 1400? For example by forcing the e1000 or virtio network device to use a mtu of 1400? Greetings, Alex
So i Need to do this inside the vm? My Problem is, that i Need to set the mtu to 1400 to get internet Access. However i Cent set the mtu during linux Installation....
you can try to force mtu 1400 on vmbr, but I think you'll have fragmentation if your guest use 1500 at install.
ok, so there is no way to "manipulate" the guest nic (virtio or emulated) to tell the guest that the maximum possible is a mtu of 1400?
seem that qemu 2.8 support a new option for virtio-net : host_mtu=xxx https://git.qemu.org/?p=qemu.git;a=commit;h=a93e599d4a04c3cf7edcf5a24f3397e27431c027 but it's not yet implemented in proxmox
That would be awesome if Proxmox could implement that. The actual use case is Hetzners new vSwitch-Feature where the mtu needs to be 1400. So I am for sure not the only one wanting this feature..
you can try to hack /usr/share/perl5/PVE/QemuServer.pm sub print_netdevice_full { ... $tmpstr .= ",bootindex=$net->{bootindex}" if $net->{bootindex} ; $tmpstr .= ",host_mtu=1400" if $net->{model} eq 'virtio'; then systemctl restart pvedaemon and start your vm.
I would also prefer to implement this option in Proxmox. It worked great with your modification and the Vlans from Hetzner.
