Not sure, but I just started having trouble with my server around the same time you did. Nobody can connect to it at the moment.

I seem to have some issues with it too.. Started a server now with mistlands and sometimes it seems the hosting / cmd window gets stuck and if i press enter on it, it can "wake up" and ppl are able to connect again.. Seems it isnt workking as well as before or Something ♥♥♥♥ up on my end but idk what it is

I have the same problem, when someone logs out, others can't access doors or chests for a minute or so... don't know any workaround sorry.

Also sometimes no one is able to connect and I fix this by restarting the server (I use dathost)

also when Mistlands came out yesterday we started getting lags and disconnects every few minutes on our dedicated server, it's impossible to enjoy the new content with this... Wonder if it's a hosting issue or Valheim issue