My step mom had trouble with her Buffalo due to a bad Ethernet cable.
Or maybe there's radio interference? I made sure our Panasonic DECT 6.0 cordless phones run on a different frequency band.
I've got 2 Buffalo G54 boxes and a recent Buffalo Nfinity that have worked very well. I don't recall even updating the firmware on them. The Nfinity gives a choice of running some open source version but I haven't tried it.
Note that I don't use DHCP as that seemed temperamental long ago. But visitors do and don't seem to have issues.
Sorry you've had issues. :-( I know this doesn't answer your question, but I hope it helps anyway. :-)
Good luck.
Cheers,
Scott.