I have an old 803s hotspot, and would typically get 5Mbs u/d speeds. I recently got one of these 6100D routers to test and was quite disappointed with the speeds, which were typically under 1Mbs. I have a sprint tower maybe 1.5 miles away. After looking online I found a few comments that people were getting faster speeds with the 6100D if they disabled certain bands. I tried this myself and got better results, yet I'm disappointed in this this device, since it is supposedly a sprint spark capable device.
To disable specific bands:
#1. you need to get the msl for this device.
#2. after you have your msl, you'll need to use ie11, or possibly chrome (firefox and ms edge won't display the info correctly)
#3. go to: 192.168.0.1 and enter your username and password (default is admin, and password)
#4. On the left hand side click on: settings then the network tab. At the bottom is a button for "advanced settings". When click it, a box pops up requesting the MSL. I made band 25 priority #1 and disabled band 26 and 41 (this made a huge difference for me but ymmv)
here are some tests that I ran with all bands enabled, some disabled bands, and some tests with bands 26 and 41 disabled: