Lenovo N23 laptop can't find T-Mobile Home Internet network...

In addition to what @copz1998 suggested, there are two other things that might be getting in the way of the Chromebook.

1. Make sure that the Hidden switch is set to off on yourT-Mobile network settings. You can get to it via the phone app. Tap the Network tab on the bottom of the screen, then tap your network to see your settings. Scroll down to the bottom and make sure the Hidden switch is in the Off position. Scroll down and click Save and your gateway will reboot.
2. If the above doesn't help, create a new network with only 2.4 GHz and WPA/WPA2 enabled. Again, to do this, go to the phone app, tap the Network tab at the bottom of the screen, then the + sign in the bottom right. Give your network a new SSID (name) that's different from your main network and then choose 2.4 GHz and WPA/WPA2 as security. Make sure the Hidden switch is set to Off. Tap Save and your gateway will restart.

Let us know how you make out! Good luck!