A customer has a network composed from a LAN shared-media (with hub 8-ports), a router linked to three modems wich link to three 9.6 kbps radio links. These radio links have linked to another three modems and PC remotes. The problem is that in LAN side, we communicate with only one remote PC, and the other two remote PC can't do it. What could be the source of the problem? Maybe CSMA/CD?