How to go about troubleshooting this problem.

We have a customer that is getting a very good signal to our tower. We are using the 900Mhz APs. He has two next door neighbors that connect just fine. When he connects however, he connects to a separate access point. He is getting a good signal (RSSI around 1200 and Jitter between 3-5). The problem however is that is losing signal a lot but gets it back fairly quickly. When I go to the AP evaluation page he can’t even see the same AP as his neighbors. His house is a little lower in elevation and I’m thinking it’s possible that he is just getting a bounced signal. What would be the next step? Possibly putting the SM on a tripod?

What do you mean when you say that he connects to a separate Access Point?