I'm pretty sure everyone experienced the same issue you're having with the server disconnecting every 1h30min mark. I talked to Nabiil about the issue, though, but I believe the server does this to prevent any ghost servers that are appearing in the lobby menu. The only solution is to host a dedicated server while the game devs are working on the issue (Although Nabiil did contact one of the game devs about it and received no response so far).

Hope this helps!

~Sorukun

I am glad you're enjoying my maps :D
As Sorokun said, there's nothing I can personnally do on pavlov's official servers, I hope they'll fix that issue at some point.
But yeah, the dedicated servers made by the community prevent this, so you should join one of those Oasis/Pandemic servers ;)