The next most likely cause of a client connectivity problem is protocol configuration. Protocol configuration issues are usually on the client side of the network. On a TCP/IP network, each client computer must have a unique address in order to participate on the network. Failure to obtain addressing information automatically could indicate a problem with a DHCP server. You should check the DHCP server to make sure that it is functioning and that addresses are available for assignment.
Beyond basic protocol issues such as addressing, remote connectivity troubleshooting also brings with it the additional considerations of authentication protocols. There is one basic rule that applies to all such issues. If a client in a remote connectivity solution is configured to use one type of authentication protocol, and the server to which he is connecting does not support that protocol, the connection will be refused.
Troubleshooting Small Office/Home Office Router
As more people choose to use broadband Internet connectivity methods such as cable and DSL, the use of compact hub/router and switch/router combinations has become commonplace.
Most SOHO routers are, in fact, more than routers. Most are also Ethernet hubs or switches, making it possible to share an Internet connection with other systems on the network. They also typically provide basic firewalling capabilities and, in many cases, DHCP server functionality.updated