Comment 7 for bug 1861457

Maybe it would help if we describe the flow of upgrades:

The cloud started with neutron packages at 14.0.2 on the computes, n-gw and n-api;
- A charm upgrade for trilio on the computes ran apt-upgrade, which moved the computes to neutron 14.0.4. This exposed a different know issue, which needed to be resolved by moving n-gw and n-api neutron packages to the same rev.

- We performed apt install neutron-common to n-api, and ngw, moving neutron to 14.0.4 there as well.

- Still experiencing networking issues we ran apt-upgrade on n-gw and n-api, and restarted all non cleanup neutron services. Then we observed the log messages posted in this ticket, and finally resolved this issue by forcing pyroute2 to 0.5.6, and removing and re-adding all preexisting ha-routers from their l3-agent.