MacBook Pro Cannot Connect to Certain/Some WiFi My MacBook Pro (2011), with OS X Mavericks, can connect to WiFi in some U.S. homes perfectly fine, but not other homes in the U.S. The "bad home" with WiFi where it fails to connect has other computers (not Macs) that can easily connect to its WiFi. 

I have tried restarting the WiFi router in the "bad home" but it doesn't fix the problem. I have also tried using the WiFi Diagnostic Tool (starting with the exclamation mark) twice, but it couldn't solve the problem either.

What could be wrong?
Perhaps the "bad home" wifi is using channels 12 or 13?

The answers to this question might help diagnose if this is the issue.