Hmmm firmware was the main issue with that...when i got the new baby monitor it was killing my connection bad and that took care of it...i'm sure you did, but you set the module option to use the ext antenna? You could try the diy ethernet board, think its something like $35. Theres also a setting (when ppl were having problems before the 4.x) to rejoin frequently...just something else to look at...
Anyway, other options to monitor power if you have a free float switch port you can rig something up with about $10 in radio shack parts and a spare ac/dc transformer...