5268ac gateway -- Wi-Fi 2.4 GHz automatically re-enabled itself, now I can't disable
I run a Pace 5268ac gateway as a modem only, with an Asus 3100AC to handle my home wi-fi and wired connections. I am familiar with accessing the Pace gateway settings, and have been using this setup with this router and two or three previous ones for the past 5+ years. I had been experiencing some intermittent slow and unstable wi-fi on the devices that use it lately, so I investigated and found the router needed a firmware upgrade. I performed the upgrade, rebooted all of my equipment, and everything is up and running.
However, after rebooting the Pace gateway, I noticed that the 2.4 GHz wi-fi band has re-enabled itself and can no longer be disabled. When I access the wi-fi section in the gateway setting and click on the drop-down menu that currently says "Enabled" next to the 2.4 GHz band, I can see the option to select "Disabled," but it can't be clicked. It doesn't even highlight when I hover over it like the other drop-down menu selections do.
My guest network and 5 GHz networks are still disabled. I haven't tested yet to see if this is causing me any NAT issues on my wi-fi reliant devices, but I imagine it is or eventually will. Is this a new feature that requires wi-fi be enabled on? It looks like I am running firmware version 220.127.116.112191, which as far as I can tell dates back to 2017, and it is the most recent event in the 5268's upgrade log. I haven't really messed with the Pace gateway since I upgraded routers maybe a year to a year and a half ago, so I won't rule out the possibility that it's been this way for a while and I just didn't notice. If that's the case and it isn't causing me any connectivity issues, I can live with it. Just curious if AT&T forces a wi-fi channel on and if so, why?