The switch from UDP to TCP is due to packet loss on the Internet connection. This can happen for many reasons and in many places along the way to your computer or from your comptuer.
The most likely issue is some router is struggling on the Internet to keep up with its load. Easy way to tell is to run Ping Plotter to 206.16.60.38, immedaitely, after losing your connection to the game server or after the switch.
If no packet loss is present, then it could be a local computer issue where your computer is running out resources and simply cannot keep up with all the game's requests.
Other issues will show when it is a resource issue. Like stutters in the graphics, pauses, skipped sounds, and possibly others. See the "Hint and Tips" post at the top of this forum for more information about this.