Just got a reply from Proxmox Support (Alexander), they're on it.
In the meantime, the workaround he provided is simple:
In /etc/network/interfaces, move
from the bottom up "above the vlan-interface where you define the gateway".
In my case, i placed it right below the sdn-bridge.
now works properly, the default route doesn't vanish anymore.
In the meantime, the workaround he provided is simple:
In /etc/network/interfaces, move
source /etc/network/interfaces.d/*from the bottom up "above the vlan-interface where you define the gateway".
In my case, i placed it right below the sdn-bridge.
systemctl restart networking.servicenow works properly, the default route doesn't vanish anymore.
