My game chat connection has now disconnected twice due to too large header in the http requests and in both cases the forum cookie that follows what threads I've read in the forum has been the culprit (bb_thread_lastview). Deleting this cookie restored the chat connection.
Reason why this cookie data is sent to the chat server is because the cookie has been configured for thesettleresonline.com and all its sub-domains and not correctly only for the forum.thesettleresonline.com. This cookie data is also sent in every game connection request. The data is not much but when it's sent in every request made to the server it must have affect on the overall performance of the game.