Jisti Win10 client losing SIP connection

Hi

I just installed the Jitsi Win10 client (2.10.5550). I can log in using the SIP credentials from my SIP provider. The client stays online for about one minute, and then switches to “offline”. During that first one minute, I can make calls and receive calls.

Any ideas what’s going on here? Could be a firewall issue, but why would it work for about one minute before it stops? Any ideas how I could trace this?

Any help is appreciated!

Peter