Oh, yes, that problem is gone. It was a stupid mistake from my part - it's a little confusing to be registered with the same account from two different computers and expect the server to know to which account to send the acknowledgements back (although it knew to send the RTP traffic to the proper client). With proper registration, from any client (including Bria) - whether it's behind a VPN or a direct connection - I don't get regularly disconnected. I know this all could be improved a lot but the standard is vague - when you have to deal with all sorts of servers and clients on the other side, you can only rely on the standard, and when that is not clear enough...
Right now the only disconnections I am experiencing is when I first establish a connection, sometimes as I start my video (or the other client starts their video) it will freeze and then say "Could not start video" and drop the connection. After a couple of retries, though, it usually starts working. The bandwidth configuration is a little confusing in X-Lite - it's hard to make it use less bandwidth. I recently had a connection with someone whose video looked very pixelated (over the entire call, which lasted over an hour) and even though we tried adjusting the network connection speed, it would not change from the 512 kbps (most of which for video). But don't let me hijack this thread!
Kamen