Failed logons after changing DHCP scope

I went from a private Class C address to a Class A. I changed the IP information in the router and was able to ping outside of the LAN. I changed the server IP, SM,GW. I deactivated and deleted the scope in DHCP. I created the new scope with router,DNS(outside), WINS,WINS 0x8. Clients are rebooted and cannot logon. Cannot find a domain controller to validate logon or check username and password. The clients are Win98. Running winipcfg shows the correct IP information from DHCP. I can ping fromclient to server IP address. If I ping by host name the old class c address is displayed and request timed out. Try removing TCP/IP and no luck.

TIA