Since the firmware upgrade i have had issues with the router all the devices connect to either 2.4 or 5 just fine but after about 5 min if you are for example on the 5Mhz wireless you can only see devices on the same wireless band. You can nolonger ping anything on 2.4 and visa versa. 

seems almost like a bug in the AP isolation that even though it is off starts to mess with traffic. Only workaround is to move every thing to 2.4 so allow for older devices which makes the purchase of the AX 6000 redundent.

I have tried online chat support but it has been a really stuggle when i have to explain the basics of DHCP and IP allocation to the tech helping me.