The tower that we connect to is far away, it just took a hell of a lot of tinkering with the placement of the xpol 6.
Mounted it to a pretty tall bedside lamppost, put that outside on a tall desk, moving it a few cm in any direction has an effect on the performance. The 1800 tower we used to connect to, we managed to pull 60 down and 30 up or so, sim was placed in a note 4, on top of a little box, under a table in the corner of the room. It only had 2 bars of signal, but for some reason, that specific place was able to hit those peak speeds. They were just inconsistent because of congestion.
After getting the xpol 6 and trying every possible configuration, connecting to that far away 2600 tower has given good results with stability.
Both versions of the 4G sim are stable and consistent, besides when that specific 2600 tower goes down. When it does, it goes down for a day or two. When that tower goes down, we max out at 10-20mbps if lucky.