@Kevin_Z Not even 10 minutes later and I'm once again unable to connect to the 2.4G network again.

@Kevin_Z Smart Connect was already disabled, but I have since changed the settings per your recommendation to 802.11 a/n/ac mixed and rebooted. My 2.4G is back up and running for now but I'll update...

Same issue here but with an Archer AX90. 2G is broadcasting and shows available to connect, but no devices are able to connect to it. Super frustrating when all of our smart devices (lights, plugs)...