I'm paying $50 a month for this?

There is insufficient data to make any definitive observations but it is clear from the two speed tests that the jitter when the speeds are impacted is almost 5X when it is improved. The other aspect of that is that the speed tests do NOT use the same server as a reference. The poor results are from the Charlotte, NC server and the improved results are from the Pineville, NC server. Speedtest.net may reflect the "optimal" source but I find using a reference source is more helpful. I am in East TN and I use the Charlotte, NC server as a reference point. It almost always provides results that are better than servers closer. Compare test results from speedtest.net and fast.com or another source. 

There is no reference to the model of the gateway, Nokia or Arcadyan or the 4G gateway and no cellular metrics to be able to provide more helpful suggestions. The problem may or may not have anything to do with the operation of that specific gateway. A major change to another appliance may just open a new bag of snakes. 

It is pretty likely the behavior is related to load on the tower and how the tower equipment is functioning rather than the gateway. I would agree 100% if you are still using the 4G LTE gateway you should push for a 5G gateway. It might be helpful to find out if work is still being done on the local towers as that seems to be a common factor in a number of conversations regarding performance issues like you see. If you know more about the signals you receive and how well they are functioning you might be able to get some improvements. If you post the cellular metrics information it would help as you could get more feedback upon the operation. Here is a helpful chart.