If you cannot connect your printer try this.
On the T-Mobile internet app (used to change settings on the Gateway)
Go to Network > (Your network)> WPA Version.
Change this to WPA/WPA2
The WPA encryption will change to TKIP & AES
Now set up your printer. You may need to use manual setup but try Easy Setup first. After the printer is setup, change the settings on the Gateway back to WPA2/WPA3.
Hope this helps.