I finished up a job this week for a company which has a peer-to-peer network which lost their Internet connection after someone jacked with their DSL modem while trying to install a wireless router. They had a Zoom DSL modem/router with DHCP enabled. I could not get this router or an identical one working even after talking with Zoom tech support. The company requested a new modem from AT&T, but began having network issues in the meantime. All the computers on this network use some kind of commercial firewall – either McAfee, Norton, or AVG. All three of these products wreaked havok with me changing routers and such. I had to end up assigning static IPs to each computer and going on many computers’ firewalls to either trust the network and/or specific IP addresses. So if you run into trouble with a peer-to-peer network not seeing computers, check the firewall settings and make sure the firewall trusts the network and possibly specific IPs if there are still connection issues.