I'm back - sooner than I thought so I'm back at square 1. I followed your instructions below but don't see the Key Things that you mention. Not sure what to do.
What is that router model number?
The Settings you are looking for should be under Home Network...Wireless tabs.
Perfect. That is a BGW-320 router. Yes, those setting should be under Home Network...Wireless...2.4ghz.
Should be seeing a screen looking like this. Contact me via PM if you can't find it. (click on my name...Profile..send Private Message).
@Olivas91, you may have to look under "Advanced Options" and I don't know if it matters or not that your 2.4GHz and 5GHz SSIDs are the same, but I'd separated them.
Thanks for all of your help. That didn't show up for me. I finally called ATT and after an hour, they found a similar issues that was solved earlier. The solution they came up with was to create a guest Wifi account and use that for the Roku. I didn't catch the entire rationale but what I got was that this was a problem with some Roku devices and if I wanted to change the b/g/n to g/n, or make other changes to the router, I would need to create a separate log-in/password. The guest log in already had the necessary change so that seemed a whole lot easier. ATT said there was nothing else to do on their end so the issue was with the Roku device settings
Good deal. That is also the remedy when their 5ghz channels cannot be changed to allow a dual-band device because of their use of DFS channels. (create guest network).
Is strange you were not able to find the mode change unless your BGW320 has a different firmware revision than others. Be that as it may, if you are happy with the fix, then that should resolve your issue.
An alternative fix, for future consideration, would be to use the BGW320 as a Gateway (modem), and then use another router connected to the Gateway to control all your wireless devices. Basically you just plug another router into your BGW320. This way, in Bridged Mode, your new router would be your DHCP server and you can manually change your settings and control your network from this router. (make all necessary channel changes, mode changes, etc).
I believe @renojim has an AT&T BGW210 (or at least did), so he can maybe provide some additional info.