I'm tapping away on my Titanium PowerBook G4, writing this message. My PowerBook can see both my AirPort Extreme Base Station ('amazing') and my AirPort Express ('amazing unplugged') when I pull up the AirPort utility and scan for networks.
My PowerMac G5, sitting literally inches away from my PowerBook, can only see 'amazing'. The PowerMac is sporting a brand new AirPort Extreme card. This is strange because 'amazing' is much further away from it than 'amazing unplugged'. I think this is why I am getting very poor Internet access from the G5, while the PowerBook's access is fine.
My setup looks like this:
(back of house) amazing --------------------------- amazing unplugged ----- G4/G5
'amazing' is hooked up to my cable modem, and 'amazing unplugged' is set to extend the 'amazing' AirPort network. amazing unplugged is a couple of rooms away from the G4/G5, while amazing is about five rooms away.
Based on an earlier suggestion in another forum, I obtained the factory external antenna for the G5 and hooked it up, but it doesn't seem to have helped things at all. The G5's Internet access, when it works at all, is at about modem speeds .
I'm getting a consistent four bars now that I have the antenna, but the Internet access itself still isn't working. In the mean time, I have two bars on my PowerMac G4 and Internet access is speedy.