How do I switch 5GHz Wifi to 2.4GHz on my Xbox?

I'm a friend of a friend that gets to use their wifi and the bandwidth changed from 2.4GHz to 5GHz and in order for me to play online comfortably, I needed to be on 2.4. Now, I can't access anything; but, every other device I own runs on 2.4GHz like that's an option. Of course, I understood that 2.4 is long range but weak and 5 is short but strong in a very simple manner of speaking, but I can't understand why my Xbox switched from 2.4 to 5 and how I can reverse that. I already asked my friend if he can ask the company he's with to check on the situation, but I wanted to ask here to see if there's anything I can do. I can't access his router through my laptop either, so some external solutions might be void. Thanks for any and all replies.

:)