Unable to connect Chamberlain garage door opener via 5g internet

Thanks for all the suggestions. I just switched from ATT to T-Mobile Home Internet last week and had the same problem with reconnecting MyQ app. Luckily I came across this forum and still kept my very old OnNetworks wifi router purchased at least 15 years ago when I had Comcast internet service. Plugged in to the T-Mobile gateway and reconnect MyQ app in no time. I just wonder once that I reconnected MyQ app, do I need to have the old OnNetworks wifi router continued to plug in into T-Mobile gateway?