I had similar disconnecting problems for the 1st few months i played. I tried different settings, uninstalled all anti virus, changed to windows 7, changed resolution. Nothing was working. In the end i found out it was a wifi problem. I have pretty decent internet and i can play online other games no problem but this one game doesnt work well with wifi. For a while it was literally impossible for me to connect to a room with 2 or more people.
Hard wire in or change your wifi. Or you can try you cell phone internet and see if that helps. Sometimes they are more stable.