Undoing a static allocation in home hub 3000

[SweetWilliam]

I made a static allocation for a computer in my home.  I now need to undo this, and return the computer to the status of getting its address allocation from DHCP.  I tried using "Forget Device", but that appears to have put the modem into a state where it will not respond to the device at all.

How can I get the modem to start responding to the device again?

[SweetWilliam · Accepted solution]

SOLVED Turns out that I had a part of my internal network that had failed, so the computer in question was not able to communicate with the Home Hub.  Once I repaired this link, the modem was able to respond to the device.