ROS guest Virtio ethernet MTU problem

I’m running ROS 6.x as guest under Ubuntu KVM host. Ethernet is virtio, all working pretty nice.

Now I want to try MPLS and have a problems.
ROS does not detect L2MTU of Virtio NIC, so I think nothing will work.

What can I do?

BUMP I have the same problem

MTU over 1500 seems very problematic