Xbox Series X doesn't want to connect to 5GHz connection.

For some reason my Xbox series X doesn't connect to my 5GHz WiFi. My Xbox One S which is literally right next to my Series X connects fine, and gives me 260mbps download speeds. My series X on the 2.4GHz connection gives me 30mbps download. I have no idea why it won't connect. It has connected one or two times in the past but every time I turn it off and on it resets to 2.4GHz.

I use a BT Smart Hub 2 with a wireless connection, but it shouldn't matter that it's wireless - the One S is actually slightly farther away from the router than the Series X which is having the issues.

:)