Naming devices connected to Home Internet

Personally I already had all my devices (86) named and managed on a Asus WiFi router. So I decided to just plug that into the T-Mo gateway and turn off the WiFi on the gateway.
They really did make this like a plug and play and it doesn't have many options for good management.

You did mention those numbers, I am thinking you are talking about the WiFi hardware mac address that is 12 number with colons. On the WiFi devices you have connected you can find this same number on a label, or on TV's, laptop's, tablet's/phone's you can see this number in the settings probably in the info or about menus. Every device is different so I cant give specific instructions but you can google how to find WiFi MAC address for "insert device" and get instructions for that device.
This is what I had to do originally when I set up the management on my asus router since some of the host names didn't show up on the router. So I used the MAC address to identify what they were. You can usual identify the device with just the last four number and letters of the MAC address. I put this information in a spread sheet, or a text note for future reference.

Unfortunately when a wifi connected device shares a name and it does not always share the host name that you name it or the name you give the device. And now that I am looking at it I guess you can not change the name on the app once you find the device my the MAC like I can do with my Asus router. That means you have to depend on finding that device with the MAC address and doesn't make it easy to manage the network unless you are just setting up a repeating weekly schedule for a device to not have access after 10pm or something like that.

NOTE: I do not have the latest firmware yet, so I don't know if what I sated has changed with a newer firmware on the gateway.

Personally I prefer to have more insight to my network and control my devices. This gateway just doesn't have those options. I think for my monthly cost savings it's worth buying another router that can give me these options. It will still pay for itself in a few months of what I am saving on the internet cost.
Or if you have one already that worked with your old internet you can plug that in with a network cable to the T-Mo gateway and use it.  Just make the WiFi networks the same name and use the same WiFi key, turn on the router WiFi and turn off the T-Mo gateway WiFi. Just turn off the one you are connected to last using the web interface to the gateway. NOTE: The phone app for the gateway may not work when connected over another router behind the gateway so you will have to use the web interface address so check the signals.