If "host switches from UDP to TCP" successfully, you wont see much difference in the game (except that you might loose vox and probably have more lag/warping/instability in the connect) - it just means that the communication between your computer and the server at HTC got switched to another protocol (ie they are talking in a different "language".
If that happens EVERY TIME you log in, check your firewall settings for AH, it needs to allow full UDP.
