Many users have reported that doing *#mac0wlan* (*#62209526*) has been giving incorrect Mac Addresses. This can cause problems for people trying to set up there N80 with there home wireless network.
In most cases, its reporting the mac address but with numbers shifted to the left once, and the first number being at the end.
Eg: 01:6b:c8:3a:d4:50 instead of 00:16:bc:83:ad:45
I have seen this myself on one of my old N80 handsets.
My new handset however has a slightly different problem, it reports the end digits as 83:ad:45 when infact its 83:ad:46!
If you have been having trouble setting up wifi, with mac blocking enabled, first try setting it up Without mac blocking turned on. Once it is working fine, go into your WiFi routers status, and you should see your N80s *REAL* mac address listed, if it is connected.
God knows how nokia have managed to include so many bugs in this phone!