Upload speeds much faster than download speeds

I'm puzzled by the 2nd gateway working well for a while unless maybe you were getting another tower or something? But you did a smart thing to try going up to your nearest tower and finding something was wrong with the download when you were getting 5 bars close to it. I mean that sounds like a tower problem. If I were in your place, facing the more expensive Starlink, I'd have a look at a tower map, and see where the next closest tower is, and get on the side of your house where that is, either outdoors or with the gateway in a window facing that tower. If you can pick that up at all, you might do well trying an external antenna. Otherwise you're don't have options, given that TMO can't verify that there's anything wrong with the tower.

When troubleshooting these issues, it’s worth paying attention to the band(s) you are on, and the metrics in the dropdown arrows when both Overview and Status are selected in the left column of the GUI at 192.168.12.1

Do you know if you were on the same band(s) when the trouble started as you were when the speeds were good for your first weeks?

I understand that you used the gateway when testing near the tower and had your phones on wifi, but are they TMO phones by any chance and when the gateway went so slow, what were your phone speeds at home not through wifi?

Also, to absolutely verify it is that specific tower, you can take your gateway near another tower and see what speeds you get there. I find the ookla 5G tower map online the easiest to use to find other 5G towers in the area.

Varying speeds is one thing, but you are right in that speeds shouldn't be varying down to unusable, and I think of that as anything below 30. I'm 5.1 miles from the tower and get 200 to 400 down, and 30 to 45 up on combinations with the mid-frequency n41, like B2/n41 and B66/n41. Before this, my best choice was 7/1 speeds on DSL. I'm very lucky to get reliable service at these speeds for the last 6 months, but one big thing in my favor is almost nothing between me and the tower in the way of obstructions. Another is not a crowded market as far as number of customers on the tower.

I've only called customer service once, as my secondary signal went out and my speed dropped to like 50. But the guy was very helpful and told me it was a problem at the tower and there was a ticket out to fix it, and it had been reported by others. A problem like yours should be something that is reported by others also. Even though they in effect said, we've done everything we can do, if you call in the early morning hours, you can always get straight through and they're not busy then, and I would just tell them what you did with the gateway to test your tower. They should appreciate your initiative and understand that shows how much you want TMHI to work for you.