I had the same issue. I ended up contacting Sprint on Twitter. We exchanged a couple of DMs and then Sprint moved to a trouble shooter on the web and finally had a trouble shooter call me. After some time troubleshooting remotely, they decided to replace the unit.
The replacement unit works well. See the SCP shots before and after in my home taken with a Galaxy S9..
Additional comments: While the MB is not up against a window as recommended, I can get a MB signal on the public street in front of my home. Makes my remote garage door opener on my phone more dependable. Same for my Nest connection on my phone.
I see a difference on both my HTC One M8 and my new Galaxy S9.
HTC One m8 Speedtest in house WiFi verses Magic Box. Not sure how these numbers compare to the norm around here. A moment later, Sprint beat my WiFi upload at 5.12 MbPs.
