The logical place to start with YOG debugging is to make sure the YOG messages themselves are being serialized properly. This requires extending NetTestSuite.h/.cpp to all of the messages in net message. I stopped doing this, after writing the script add_net_message.py, all NetMessage classes where generated by the script, and as such never had any bugs. However, if one feels its needed, test cases can never the less be added for all net message classes, just to verify the bottom line is working properly.
After that, I don't know where to begin. Reproducible sequences that involve running a fresh server, and logging into it and doing whatever that results in an invalid state need to be found. What I believe is happening is that the server is going into an invalid state, causing problems for both players and eventually crashing the server. I can't verify this for sure, its likely a combination of bugs in both client and server code. The bug could be as simple as a buffer overrun or something like that, causing systemic problems for all of YOG. These reproducible sequences might be long, involving starting a server, logging in with several different accounts, playing, starting and stopping a number of games at the same time and consecutivly, downloading or uploading maps, almost anything that is doable on YOG. Eventually, we might be able to narrow it down to the problematic things to do.
-- Extra cheese comes at a cost. Bradley Arsenault.