I did finally fix that. The reason was incorrectly configured TURN (coturn) server. I forgot to set realm field and because of that TURN functionality was not working. I checked that on this site https://icetest.info/. Also not sure if that was important but I uncommented fingerprint property as well. And finally I moved on to a new VPS via different hosting service with higher bandwidth to make sure the bandwidth will not be bottleneck.