N750 and home network

Recently I purchased a new N750 router from Best Buy.  Actually, I’m on the second one.  Both are giving me the same problem.  Took the first one back and now this one is doing the same…I’m not very good and technical terms so I’ll do the best I can.

The problem is with both the 2.4 and 5 Ghz signal.  My connection via 2 MacBook Pro’s is non existance. Both devices see the signal, connect and on occasion work but then it drops it.  Sometimes for only a few minutes other times completely.  

If I connect, as I am now, wired all is well.  So I know the modem is fine and the connection via the N750 is okay.

I’ve nearly pulled my hair out trying to figure out why this happening.  The only major thing that has changed since the problem is I’ve upgraded to Mountain Lion on both machines.  Other devices (iPhone, Apple TV) appear to connect okay but not for sure.

Any suggestions on where to begin to diagnose?

Thanks!

Might be a low signal problem, also be sure to update the firmware to the latest version.