5G Home Internet is not 5G

The grey gateway is the device that receives the 5G signal, and then the router portion of the gateway delivers it to various devices in your house via wifi. You'll get a faster speed when using the wifi on a device which uses the WiFi6 protocol on the 5Ghz (not to be confused with 5G) band, but it is dual band and will also work on the older 2.4Ghz wifi band. Or, you can plug a computer in with the included cable if you want to see if that will give you a faster speed than with wifi.

By going to 192.168.12.1 you can determine whether your gateway is receiving a 5G signal, which means a non-standalone primary/secondary pair (4G/5G), by selecting STATUS on the left and then the dropdown arrow to the right of Primary and Secondary. If you are receiving a 4G LTE signal only, then it will show a Primary signal alone with no secondary.

They are issuing the grey gateway in areas where 5G is available but it can happen that for whatever reason, you can't pick 5G (the secondary band) up at your house. As long as your download speed is above 50Mbps or so, no need to worry about whether it is a 4G alone or the 4G/5G pair, as long as the speed and connection stability works well. And if you get 4G only, maybe one day they will tune the 5G differently or install different equipment such that you can pick it up.