Unable to connect Chamberlain garage door opener via 5g internet

I purchased a new Netgear extender as recommended by T mobile and I assumed it was at factory settings but using the Netgear app, it would not connect to the netgear online set up.   I sent it back to Amazon.   I have a Nighthawk extender but it connects to the Nighthawk router which did not connect to the Gateway .   I was told by T mobile that they were not compatible, so put them back on the shelf. Which extender connected successfully?   Gracias