Slow 4G connection only, but only sometimes -- SOLVED

I get b66/n41 currently which is normally guaranteed to be better than the old 10 Mbps max per phone line I got with DSL for the last decade. Speeds have been fairly inconsistent although normally (but not always!) better than 10 Mbps. I get 3 bars with b66 and 2 with n41.

I have seen over 200 Mbps but also disconnects from time to time. Usually it's over 100 Mbps which is still great for me. I've had it for 3 days now.

I like using https://fast.com/ for a quick Netflix specific test and http://www.dslreports.com/speedtest to keep track. That’s ‘http’ and not ‘https’ since the secure connection doesn’t always work with the test for some reason.