RAX50 - AX5400 5GHz timeouts

I'm having an issue with my RAX50 and my 5GHz network. My 5G network works fine for any device when that device is newly connected to the 5G network. Then over time the network becomes more and more unresponsive until all network traffic to that device times out. This happens on all devices that attempt to use the 5G network, iPads, intel Windows 10 PCs, and iPhones. All connecting devices updated to latest OS's. The distance from the router doesn't affect the outcome, you could be within a couple of feet of the router and this situation occurs. The device signal indicators show that the devices have good signal strength, and in the case of desktops they never move.

The 2.4GHz network does not exhibit this behavior.

Latest RAX50 firmware installed, V1.0.2.82_2.0.50, but issue has been happening since I installed the RAX50 and over several firmware updates.My 5G network on previous Netgear AC1900 router worked fine until RAX50 replaced it.

Fragmentation Length: 2346

CTS/RTS Threshold: 2347

Preamble Mode: Long Preamble

Thanks!