I am trying to see if the 5g output on my 4th gen airport extreme is working.it seems to be set up ok and says it is using channel 36. I am using a Proster AC600 dual band wifi adaptor in my PC just to check the local wifi signals. I can see the 2.4g output ok along with all the neighbours 2.4 and 5g signals. I have a second 4th gen airport extremes in a different part of the house it does not show the 5g signal (the second one is using channel 100). Does anyone have any idea what the problem could be.