Webmin Filesystem Backup very slow transfer to remote SFTP server

OS type and version Ubuntu Linux 20.04.5
Webmin version 2.013
Usermin version 1.861
Virtualmin version 7.5
Theme version 20.13
Package updates All installed packages are up to date

I am attempting to use the Webmin Filesystem Backup feature and am finding that the transfer to my offsite server is very slow.
The only setting that I can see that I might not have set correctly is the Remote Backup Command (RSH, SSH, FTP)
Since I am sending to a SFTP server I selected SSH. The rest of the options appear to be obvious with how to set them up.

In my tests I see that the TAR command appears to work properly and is relatively quick. I get a notification that the backup is complete when that portion finishes. The script then attaches to the SFTP server and begins to transfer the data. The time to transfer about 1GB ends up being about 1 hour. I checked my upload limits etc and calculated that 1 GB should be able to transfer in about 2 minutes. I ran several other tests and there was no change in the slow transfer time. I then tried using the command line SFTP client built into Ubuntu and transferred all the files within the folders recursively. For the 1GB of files the transfer time was about 2 minutes. I then tried the same thing with about 8GB of files and the time was 16 minutes (1GB/2 min.) This is the transfer rate that I was expecting. I then created a TAR of my original 1GB of files which took a very short time and sent it using the command like SFTP client. Again the transfer took just under 2 minutes.
There must be something that I am doing wrong when using the Webmin Filesystem Backup. I can’t see why it would be taking 30 times longer to complete the same task with the backup vs the command line client.

Can anyone provide me with some information that can help me figure out what I am doing wrong?

Tried a bunch of different settings and couldn’t get it to transfer any faster. I finally gave up and set up a cron job using rsync. Ran way faster and I can use the built in feature that checks and only uploads changed files.

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.