Emule is a "peer to peer" network that piggybacks on the internet. Is essence it is like using a 2nd language on a telephone. Only those on the line who understand the language can talk with you. However the mechanical transport from place to place is the SAME as what your browser does. Now, as to how P2P networking WORKS. Your client "pings" with a general "are you there" type of broadcast through your ISP to every network your ISP is connected to and then again to networks THEY are connected to for up to about 30 hops. The pings spread throughout the network like ripples in a lake where you drop in a stone. Anyone hearing a broadcast ping sends a reply. For each reply you hear, there is an entry made in your peer list, sort of like building a phone book by dialing random numbers and asking whoever answers who they are. You can add all you want manually, but when the time comes to check if they are there, the "are you home" ping gets no reply. After some number of attempts, it gives up and removes the server from the list. You should not ever have to add a server manually. If it isn't "found" by getting a "are you there" reply, there is no point in having the server on the list, is there? Sometimes, manually adding a server CAN result in success, because the server is simply beyond the hop limit of the "are you there" pings, in which case it WILL stay on the list because there is higher hop limit on server to server pings than there is on the general "are you there" kind that has no specific destination address. What you are doing is trying to override the automatic search the P2P network is doing to find other servers which can only work in a certain few circumstances.
