I dare to ask two questions in one go, hope this is okay.

Recently, we moved to another place which has larger distances and
thick walls. So the power at the receiving stations is low. I have
already bumped up the transmit power of the Atheros 5212 from 5 to the
maximum that I can get, that is txpowmax 32. Still not sufficient ,
alas. Now I wonder if anyone has a suggestion for a MINI-PCI card that
can deliver more and is supported by m0n0wall? I checked the hardware
list of the m0n0wall site, but no definite answer was found. Anybody
out there with a positive experience with a higher transmit power?
Likewise, I can't seem to connect reliably any longer with my TP-Link
WN-321G. It seems to suffocate the link one way or another with Ubuntu
12.04, so it looks like. A ping to the WAP at reasonable signal
strength, does usually not go through more often that 1 out of 10 or
20. I wonder if this is a known problem (of Ubuntu?). Don't tell me to
change the dongle: it is the one with the highest indicated signal
strength at further locations, so I'd like to use it. Any chance of
fiddling with MTU, or other settings? Any hints at debugging this
situation?
(it shows as Ralink, RT2501/2573 and uses rt73usb module, in case this helps.)

Thanks in advance for any hint,

Uwe