Will I benefit from band locking? Tested 4 modems

[wisem2540]

Hello,

I am a bit new to this hobby. Recently I activated a $20 AT&T Tablet plan using an old Galaxy Tab S2. This tablet is obviously not capable of 5G, and I do not have 5G service in my area. As you will see later, my personal phone averages around 100 down whenever I do a speedtest. The goal of this project is to create cheap, reliable, fast internet that will be a failover to my 500Mbps Spectrum connection.

I have ran 4 basic tests from my kitchen table (hardly scientific). Each test was done from the same basic area multiple times. No IMEI work, no Band locking, just inserting the sim and running a speed test over ethernet on a laptop.

Netgear LM1200 4G Modem (Tablet Sim)
Netgear MR1100 (Moxee Work Sim due to size)
Netgear MR5100 (Tablet Sim)
Work-provided Moxee Hotspot (different sim)

Galaxy S20+ phone (different sim) (Control) - this device averages around 100Mbps download consistently.

- LM1200 ($105 New on Amazon) - 20-25 Mbps
- Moxee (work provided AT&T) - 20-25 Mbps
- MR1100 ($90 Used on ebay) - 50-80 Mbps
- MR5100 ($225 Used on FB) - 120 - 180Mbps

As you can see, the MR5100 outperforms all others by a pretty wide margin. All without 5G and without any tweaking. So, my question is:

Is a 60Mbps speed spread normal for cellular?
Will Band locking potentially unlock higher speeds or perhaps close the 60Mbps gap?

I have not tested any of these theories because I do not know what I am looking for. How do I identify the best bands in my area? How to I properly pair them for Carrier Aggregation? There seems to be very little information out there for people who are just learning, I cannot even find valid AT commands for the 5100 or a simple guide on how to test band combinations. But, overall, if the benefit isn't there, I may just keep everything default. Any help to learn what to look for would be huge. Thank you