MAC filtering works great if you know what you're doing. That was my problem. When it comes to wireless networking I'm a newbie. My initial devices were configured for me by the trial software. I tried to add the Nokia N800 manually after the trial period expired, and not knowing about MAC filtering, I could not get the device to connect no matter what I tried. The MAC Filtering configuration is not on the Setup tab. I found out from tech support it's on the Advanced tab.