Uninstalled server 2008 now router won't handle DHCP

Uninstalled server 2008 now router won't handle DHCP

My set up is this. server behind router, router has a server and switch
connected to it with multiple computers. router used to serve DHCP and
DNS, a couple of days ago installed AD, DNS and DHCP on the server, and
the server gave out IP's.
For various reasons we had to uninstall the domain on our server. I
removed AD, DHCP and DNS from the roles and set the router back to serving
DHCP and DNS. Now I can't get computers on the network. I reset my router
back to factory defaults, and if I plug a computer directly into the
router I can get a IP address, but all the computers behind the switch
can't get an IP address and can't see the router. All my computers say
unidentified network, and if I ping the router it says host is
unreachable.
On the other hand, my wireless devices are just fine and connect no
problem. But for desktops, ipconfig /release doesn't release anything and
/renew can't find a server to renew on. My router log shows several FIN
scans but they are from innocuous websites (google, netgear) and it shows
a couple of smurf attacks but they are all from my external IP. Any ideas?
the server isn't even connected to the route right now, and all the
computers are set for dynamic IP addresses.. I don't know what else to
try? Any help?