I had some force closed connections issues. Basically OneDrive was closing the connection, forcing rclone to reconnect and slowed everything down. I always use the --disable-http2 flag for that reason and have experienced a way more stable connection.
I was copying a couple of media files that I know cause freezing (one one of them it happened repeatedly this morning) from OneDrive to the server storage itself. The purpose was going to be to play the files from the server, to see if the connectivity between OneDrive and server was to blame.
During the rclone copy, I noticed the transfer rate was generally around 35 to 40MB/s, but occasioanlly dropped to 10MB/s. I thought this would cause freezing (if freezing is a network connectivity issue which I assume at this point it is) on some media files, however it would have to persist for several minutes as I have restored the vfs-read-ahead 2G flag.
Never mind, the killing blow came near the end of one of the files; the rate went down to 5MB/s and it stayed there for 10-15 minutes, before going back up again. No amount of vfs-read-ahead that I can possibly use will cure that.
There is no mention of anything odd in the logs. So it seems the rclone transfer randomly drops to below the required rate for these files, hence the freezing happens - this makes good sense.
Now, since no mention exists in logs, can I assume this is not throttling but just some connectivity issue? And if so, is there any combination of rclone mount settings I have not yet tried that II can use to mitigate it?