Slow file-transfer over local LAN (Gigabit) between Linux-Client and Linux-Server

I’m new to UrBackup and having very slow file-transfer over local LAN (Gigabit) between Linux-Client and Linux-Server (having UrBackup installed).

The file-transfer from Linux-Client (Backup-Client) to UrBackup is shown with less than 1 Mbit/s! I’m trying to run initial full-backup running at 505.11 Kbit/s estimated for 3 Years runtime :face_with_raised_eyebrow:

The Server is an IBM x3400 with 6 CPU Cores, 12 GB RAM running Disk-Storage with RAID 10 and 2x 1 GBit NICs running VMware ESXi. The UrBackup VM-Instance has 4 GB RAM and 4 CPU Cores assigned. I don’t think that the Server is the bottle-neck.

Initially I thought there may be some physical bottle-neck in Network. But I’ve checked this with the Linux network-tool IPerf3 (installed on server and client) to benchmark network speed between Client and Server. IPerf3 is showing up to 900 MBit/s transfer rate. So I also don’t think the lack is on the network hardware/cables.

I already checked a bunch of “Slow transfer speed” threads here in forum. I also disabled “run backup on client in background-mode” which obviously seems to slow down the whole thing. I also tried setting backup-speed to 500 MBit/s in Client and BackupPC Settings. Still no glory in network speed.

Why is UrBackup running at slow speed?