Splitting 2gh from 5gh so I can connect my HP printer to wifi

On the Wi-Fi settings page, click on Advanced Settings.  Then you'll see the two separate bands so that you can give them unique SSIDs.  And, as Constructive says, ignore the dire warnings about disabling band steering.

You could instead just enable the Guest SSID.  It is 2.4 GHz only.

you need to login to your router and in the wifi section give the 2.4 and 5 their own different  unique username and password 

ignore the warning for band steering

Also click on advanced and change the Chanel setting from find best Channel automatic, and use WIFI Analyser on an android phone that supports 2.4 and 5GHz like the TLC 10L ($159 like new from Amazon) to find and recommend the least congested Chanel’s.

don’t use the built in AT&T a congestion survey….it recomends channels that are the MOST congested !

Locking your channel can be a good idea to keep your clients from having to try to follow the Gateway around as it switches channels trying to find lower congestion; find one and stick to it.  Only choose channels 1, 6 or 11 in the 2.4 GHz band, never the channels in between.

Yep, I’m on channel 1 for 2.4Hhz and Chanel 149 fir 5Ghz locked. It’s now stable as a rock. Oh and DONT use AT&T DHCP DNS. Manually change you client computers tablets and phones to use 1.1.1.1 , 8.8.8.8 and 8.8.4.4.

Google and Cloudflare actually pay a lot of money for highly skilled Admins. Where as i suspect the peanut 🥜 barrels are getting a bit low on feed for the AT&T Admin (singular???) 🤣🤣🤣🤣🤣

AT&T DNS works well for 99.44% of cases.  There are situations when it struggles.  You can use other DNS with your clients (if you feel the need) or if you use your own router behind the Gateway, you can put it in its DHCP handouts.