how do I displaying 2.4ghz?

INSTRUCTIONS

You can have several Wi-Fi networks on the gateway.  You want to leave the default network alone (2.4 & 5 GHz; WPA2/WPA3 and AES security) and add a second, dedicated 2.4 GHz network.  This second network is for devices that can’t connect to the default network.

Add the second network with the + sign at the bottom of the Network tab in the T-Mobile Internet app on your phone.  For this new network, set the band to 2.4 GHz and set the WPA version to WPA/WPA2.   (The encryption will automatically change to “TKIP & AES”)  Try connecting your device to this second network.

Use the default network for your other devices, as much as possible.  Note that WPA/WPA2 (on the second network) is less secure, so I recommend setting this network to be Hidden. You can hide it after you get your devices connected to it.

Here are the T-Mobile support instructions for how to add the second network with the app.

Android  How to create additional Wi-Fi networks | T-Mobile Internet app | Android | T-Mobile Support

iOS  How to create additional Wi-Fi networks | T-Mobile Internet app | iOS | T-Mobile Support

Main instructions

Help Center | APP Android | T-Mobile Support

Help Center | APP iOS | T-Mobile Support

@Maddjack I think you can probably improve your download speeds with re-positioning the gateway.  You might need to try another room, especially if is in a room far from your TV.  Use the Speedtest by Ookla app on your phone, connected to your Wi-Fi. Measure the speed near your TV.  Measure the speed near your gateway.  There will be some drop-off, but you can use this as a method to experiment and find the best location.  You can also try rotating the gateway.