Another consideration to take into account is that this should not be the exact same setup. An antenna which previously connected directly to an AP-4131 would require an antenna adapter to connect to the AP-5131. The addition of this adapter would cause some insertion loss, which could be contributing to your difference in coverage.

Hmmm.  Didn't know that.  So why would the AP report 20dbm (100mw) in the gui if it really is 17?  Can you help me understand that, please? thanks, Greg

Yes you can give me a call for the long version but the reality is they turned down the power on the radio and did not correct the GUI. They do the math assuming you put on a 3 dbi antenna on the 5131 then you come back up to 20. It has somthing to do with the two dual radios but I have been burnt big time on this and have sat in a room and watched my customer measure the power  at the interface so I have seen it 1st hand. If you want the same coverage you need to buy a better antenna than you are using on the AP4131.

Folks,if the AP output is 20 dBm (100 mw) or 17 dBm (50 mw) doesn't really matter.Don't forget that Networking is always a two way communication.Said that, please consider the output power of the MU.Most of our MU's are running 40 - 50 mW only!So what is the benefit if the AP range is 100m, but the MU range only 50m?The MU may "hear" the AP, but the AP can't "hear" the MU. So this will not work.You have to use a high gain antenna if possible, because the antenna gain will help the AP to hear the MU much better. in that case you have to reduce the AP power anyway.So don't forget to consider the MU power and make the math again!Regards,Angelo

It is not a one for one replacement. The real power at the interface of a 5131 is only 17 dbm not 20 dbm. this is basicly half the power of the old 4131