I’m seeing about 5-6MB/s on a 40MB/s connection. I thought this was an issue with B2 (using B2 backend) so I tried using iDrive S3 and seeing exact same speed making me think there is something else going on. I tried changing the read-concurrency and b2 connections and saw no improvement.
If I set the S3 connections and read concurrency to a crazy number like 50 I can push almost 7MB/s but that’s the best I can do.
Does it make a difference when you upload a single big file? Also just to make sure, do you have a 40 Megabit/s or Megabyte/s uplink? Because if you have a 40Mbit/s uplink this sounds really reasonable to push ~ 7 Megabyte per second (as sometimes the uplink can be faster).