Cayman 3220-H Gateway locks up network

On a 4 pc peer-to-peer Win98 network, Bellsouth DSL was just installed with a Cayman Gateway supplied by Bellsouth. When the pc’s are hooked up to the Gateway, it constantly locks up the pc’s on the network. When the pc’s on hooked up to a hub, noproblems. Bellsouth claims this is not a router problem, and Cayman is impossible to reach. Is this a configuration problem or a hardware problem? Thanks for any input you may have.