1. The reason for bad ECM is bad internet connection (no matter what is the speed, internet should be stable), or bad connection between PC and tuner (if any) (COM port).
2. When you enter the information to EMU, you create different lines containing server name (IP), port No., login-password, etc. - for each server its own settings. So, when you run EMU, it starts searching the port, channel etc from the server it is connected to. If it does not find the right one from one server, it starts doing the same from other servers- one by one. If you proscribed certain ports for our server, sure that EMU will look for the server and ports you just pointed out clicking the channel you want to watch. In the case if EMY does not find the right channel from our server, it starts looking for it from another servers, etc. until it finds the right one. It only takes time while EMU is looking for the right server, port, etc.
If you are using onboard DVB-card, it is possible to copy the folder with the software installed (suppose, ProgDVB) and create its copy (renaiming it) without additional installation of the same software. You may create as many copies as you want, each copy provided with it's own EMU for particular server. That is the best solution to avoid ban from any of the servers you are connected to.