Smoline, Have you tried connecting a non-Mountain Lion computer to your Gen 4 network to see if it gets higher speeds? It could be an older Mac or a Windows computer. Maybe a friend or neighbor with a laptop could try it. -- Upstate NY HN9000 Apple Airport(802.11n)/ Mac OS X 10.6
Bill: Yes, we did that. It was one of the things we did to isolate the problem to Mountain Lion. A Windows machine on the same modem got the advertised speed. In fact, even a Mac with OS X Lion (10.7) received the advertised speed. The issue is limited to Mountain Lion, and any devise running iOS 6, like an iPad or iPhone.