How did you come to the conclusion that servers with port 7777 are blocked?  The reason I ask is because our server hasn't been on port 7777 until recently.  So if our server is included in your 2 months worth of problems then I don't think 7777 is the issue.  We still use port 6500 for server query information though.  How are you trying to connect to servers?  Favorites, History, through the console, server browser?