Slow file restores


After a hard drive crash, I wanted to restore the entire contents with approx. 4 TB of data. Unfortunately, it takes an extremely long time. At the beginning it goes quite quickly, but the longer it takes, the slower the transfer becomes.
After 24 hours I am now at 45%.
You can also clearly see in the activities that very little data is being transferred. Where at the beginning the almost 1Gbit network bandwidth was used, now hardly more than 100 - 200 Kbit/s is used with many pauses.
The IO load of both systems is hardly present.
The target system is a Windows Server 2016.
Client version 2.4.11
The original backup server is version 2.4.13 under Ubuntu.

What could be the reason for this?

Many thanks in advance
and many greetings

How are you restoring?

I tried an image restore with the rescue iso (Debian) and it was very slow - 2 TB and not finished overnight.

I noticed lots of call trace errors in dmesg about the network.

I rebooted with an Ubuntu 20.0.4 live cd and noticed the first nic only coming up at 100 Mbps so that may have been the issue. I recall seeing the ports come up at 1 Gbps with the BIOS so maybe there’s an underlying driver/firmware issue.

It’s a file backup. So I’m using the Server GUI or the Client. Both have the same bad result. No Warning or Error in the log. Just stopping. I try to restore now many paths under the root (F:) by hand.