I have found this to be a problem when the DHCP source is a Sonicwall. It may be a similar issue. In this case, there is no local DHCP "server" as the link is a handful of clients only (for now) and the Sonicwall is handling the services I would normally have on a real server.
I wonder if anyone else has noted this using Sonicwall VPN/Firewall? Maybe there's an adjustment on the Sonicwall we can make.
I had to force a local IP address (static). It would have gotten one anyways, as you noted, static is a better plan, however during initial setup we were also testing DHCP assignments and the B5 station did not get one...Yet... clients connected and got assignments as expected.