Range Extender EX3700 AC750

I have had the EX3700 working for maybe a year with a Linksys router. I replace that router with an ASUS RT-AC68U. Did a factor reset of the range extender and a fresh setup. The range extender keeps showing no internet connection on the 5 Ghz band even though setup and the green lights indicate a connection. I just spent maybe an hour with Netgear tec support and they had me go through the reset and setup procedure twice also. I purchased a brand new EX3700 as tec support suggested and it does exactly the same thing. The setup procedure runs and looks fine; I get all 4 green lights on the range extender. But windows keep showing no internet connection on 5Ghz. and my browser goes nowhere. Maybe this is a compatibility issue with ASUS and Netgear, I don't know, but Netgear tec support could not resolve the issue. I have no problem connecting straight to ether band of the router itself.