There are three issues here that need to be clarified.
1. Is ME really acting as a server? In other words, have you tried to set this network up as a Server/Client network, or do you really mean Peer to Peer, far more common on a home system.
2. Forgetting the internet for the moment, has the network ever worked? eg. Could you share files from machine to machine?
3. If the answer to 2 is no, then sharing the internet is a non-starter until 2 is sorted out.