Custom server, unable to connect over hamachi


I used to host a BeamMP server for some friends. The setup was very simple, players who wanted to join the server joined the hamachi network and used the hamachi ip of my server to join in beamng.

Last week we tried again, but they were unable to join. They could not see the server. The server config did not change, but the beammp server and client both had an update.
What can cause this? I have changed system to a windows 11 pc. Is there any security / firewall / network setting which can cause the port or server to be unreachable?