Nintendo Switch NAT Traversal Process Has Failed

I have been trying to solve this for a couple weeks now. T-Mobile doesn't have a written script for their customer support yet. Someone I talked to said they had fixed this in the past and said they did something on their end and would process in 24 hrs. The initial non tech person called me the following day and asked if it was fixed. No. So they sent me a new device which as I suspected didn't solve the issue. Someone KNOWS how to fix it. It has to do with port forwarding/settings. Nintendo says it's because of poor signal, but I can play PS3 online. I can go to Nintendo online store but can't make purchases or play Mario kart online with my kids and I can even use my phone hotspot but not this WiFi device. So there is something that needs to be adjusted in the WiFi settings that T-Mobile is not giving access to. I imagine there are a lot of people playing Nintendo switch, and a handful of people have T-Mobile internet. So T-Mobile needs to understand that people will give THEM up before giving up Nintendo online access. Be better.