tarifa - 2010-01-07

Tarifa firmware uses udhcp 0.9.8, this is the updated version of the one in the stock firmware.
DD-wrt uses the same udhcp package with updates, tomato uses the Dnsmasq dhcp server package.

Your idea that the problem has something to do with DNSMasq is interesting, I will keep that in my mind.

To see what happens in the router, you need to enable syslog, this way it is possible to log the problem and solve it.