Could be any number of things. It's broadcasting a request for a DHCP server to give it config info and not getting a response. Usually the router has some sort of logging facility that may help determine the issue. If the DCHP server sees the request and ignores it, that's one set of problems. If it doesn't see the request at all, that's another set of problems. I could be something as simple as the router/server doesn't have anymore IP addresses allocated to give out via DHCP. Your going to have to dig out some sort of real diagnostic messages from either device to help give a clue what the problem is.
Ich bin hier und du bist mein Sofa