For the office we recently bought a WNDR3700 (v1) to accomodate our growing (from one wired and about four wireless to four wired and about eight wireless clients, so not really large) network. We have a Mac Mini server set up as DHCP and DNS server (it has a static IP), so it serves IPs and sets itself as the DNS. I have disabled the DHCP server on the WNDR3700.
What happens is that sometimes the DNS server is not reachable by most (but not all) clients.
I have verified that all clients can ping all other clients, the gateway and hosts on the internet, except that some clients cannot ping to the DNS/DHCP server. Those clients also cannot use nslookup (or dig).
I do not know about any restrictions on the DNS/DHCP server. It's logs don't state anything out of the ordinary and there are no (obvious?) errors.
Update
So the connection was lost again so I tried pinging the DNS server from a PC.
ping 192.168.1.255
gave replies from 192.168.1.2 (the DNS server), but no other machine.
ping 192.168.1.2
gives only timeouts.
Pinging 192.168.1.255 from a working machine gives replies from all other working machines on the network.
Best Answer
You need to debug this one step at a time.
First: check that computers connected to the wired network get a valid IP address, and that their DNS server is set properly. Second: check that they can talk to the DNS server (use nslookup) Third: check that there are no restrictions on the DNS server.
There are many possible reasons why this won't work, and your post doesn't have nearly enough information to give conclusive advice.