How do I resolve a DHCP issue with a fon router?

I don't know how many people are familiar with fon (this is totally not a plug, because it basically doesn't work ever) but I've been using a WRT54G router from fon with the final fon firmware for 4 years now, and a Fonera (1) for 3 years. I never used to get anyone using my Fon router, and I thought the Fonera would solve this, as it auto updates itself and apparently there were quirks frequently.

My fonera has never had a paying user nor a free user, but it's not because people don't connect to it. I've tried connecting to it myself, and the problem seems to be that the DHCP server is acting badly. Shortly after my first request and redirection, I get messages like:

IP 192.168.187.71 is in use by 00:0c:29:mac:address.

But my wireless mac address is 00:25:00:something. Does this happen to anyone else? How would I solve this issue?

Perhaps there's a way I could use a custom OpenWRT firmware to enable people to use my fon gateway while retaining better control over the actual behavior. This is something I'd love to have working right.