printer issue

OK so I can see the printer possibly has a 10/100 Mb Ethernet port or 802.11b/g/n (support WPS). The T-Mobile gateways do not support WPS so you would have to manually connect. I don’t see the authentication type supported by the printer so that is important to know. (WPA, WPA2, WPA3) Using the wireless connection you will need to make sure the gateway has the authentication type on the frequency. The manual makes reference to 802.11b/g/n so your best bet is to get it to connect to the 2.4 GHz radio vs 5 GHz. You might have to add a SSID to the 2.4 GHz radio and make sure the authentication matches to get it to work. If that printer does have an Ethernet port on it the most simple way to connect it is to use an Ethernet cable and connect it hard wired to the gateway via one of the ports on the back of the gateway. 

I don’t have one of those types of printers and have never seen one so I have no idea which model it is nor how old it is. The manual I can find online is pretty extensive but it covers the various versions of the printer so it is not clear the exact specifications of the one you have. If it does not support a newer version of the wireless communication standard it might be a challenge to get the wireless to work.