'Don't Use UDP for data packages'

[Crono]

If you uncheck it and are behind a router you have to select "Use fixed port for UDP" and enter a forwarded port or forward whats already there. UDP makes your character appear much smoother for other people and will make them appear sightly more smooth for you. When it's checked you're on TCP, and this makes your character slightly harder to hit as your character is more jumpy thus harder to predict.

[Skyld]

Originally Posted by Crono

If you uncheck it and are behind a router you have to select "Use fixed port for UDP" and enter a forwarded port or forward whats already there. UDP makes your character appear much smoother for other people and will make them appear sightly more smooth for you. When it's checked you're on TCP, and this makes your character slightly harder to hit as your character is more jumpy thus harder to predict.

Well, not always. TCP tries to make sure packets get delivered by acknowledging received packets and resending dropped packets. UDP does not do this, so on a connection where packet drops is a problem, UDP will make your character seem very unsmooth. It just depends on the speed and reliability of your connection; UDP is better on a stable connection (say, fixed line DSL or fibre, maybe dialup) since it has less overhead and therefore is faster, but TCP is better on a less reliable connection (for instance, 3G, satellite) since the packet will be redelivered if necessary to make sure it gets there intact.