If pump is started with '-h hostname' it does not supply
the hostname to the server when renewing its lease.
I've had to switch to dhcpcd, which works. It also:
1. Observes the lease timeouts supplied the server.
2. Tries to get the same IP address on a reboot.
Perhaps you could add these (good) features to pump.
Just checking, you are running pump-0.7.0, right?
*** This bug has been marked as a duplicate of 7486 ***