Ok, so what would cause this?

Replaced a nw65sp8 server doing dns/dhcp w/ an oes11 server doing the
same thing. Have dhcp service, subnets, etc, setup, service loads &
stays running. OES server w/ same IP address as replaced nw65 server.

Problem is, many machines cannot contact this server to receive an ip

No acl's, etc, server addy can be pinged everywhere.

What gives?