Nighthawk X6 AC2200 EX7700 no internet connection via wifi

I am no longer getting wifi connection with my EX7700. Currently I have four Nighthawk X6 AC2200 model EX 7700. I purchased them in March 2020.  They worked wonderfully in my old house that has plaster lath/cement walls. The other day, the wifi stopped working (no internet connection). I pressed the reset button, then followed the same process (e.g., connect cable, press WPS etc). Basically, I am following the set up as if they were first installed. To reset the devices, I placed the EX7700 in very close proximity to the router. I could not connect to the units by wifi to access the firmware updates.

My router is working fine. I moved the connection for the EX7700 to other outlets on my router and they work. When I connect the ex7700 by cable to my laptop, I am able to go in and do firmware updates etc. I am still unable to get wifi connection. I remove the wifi connection from my phone/laptops and reset them and still unable to get wifi connection.

I repeated this process with all my units and I am having the same problem.

There was a recent firmware update for these devices. However, the wifi was not working before I installed the firmware updates.   I figured the firmware was required to fix the wifi connection. but still no wifi connection. Could the wifi capacity on all four EX7700 be fried?

I have been considering Netgear Orbi RBKE963 WiFi 6E Mesh System, but once bitten  twice shy.