Slow network speeds

[Goggel]

Hi, I am setting up my first proxmox server and ran into a issue.

When I finished setting up Proxmox (6.2) I noticed that the network speeds far below expectation, about half the speed I was expecting from a 1gb connection.
(onboard Ethernet controller: Intel Corporation I350 Gigabit Network Connection (rev 01)

So, I ran iperf3 a few times this was confirmed:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 557 MBytes 55.7 MBytes/sec 0 sender
[ 5] 0.00-10.00 sec 555 MBytes 55.5 MBytes/sec receiver

Tried Ubuntu, same result
Tried Proxmox 6.3, even worse
Tried Windows 10 Pro, success full speed (113Mytes/sec)

edit:
Tested Centos linux release 7.9.2009 (core)
iperf 3 -c 192.168.1.103 -f M
[ ID] Interval Transfer Bandwidth
[ 5] 0.00-10.01 sec 1.09 GBytes 111 MBytes/sec sender
[ 5] 0.00-10.01 sec 1.08 GBytes 111 MBytes/sec receiver

Tested the same thing with a 4-port HP NC350T (Ethernet controller: Intel Corporation 82580 Gigabit Network Connection (rev 01) ,same result
It looks to me like it is a driver issue

How can I resolve this.

Thanks

Added hardware:
Fujitsu TX300 S8 server
2x Intel Xeon E5-2670v2
64 GB ram
4x SSD 500 GB Samsung EVO850
4x HDD 8TB HGST SAS3
LSI HBA

 

[Goggel]

Tested Debian today and got the same disappointing results. It looks to me that there is a problem with the Intel network drivers in Debian based distros.

 

[vikozo]

have to follow, my backup required over 8 h copy from a node to another

 

[bobmc]

might this be worth trying?

https://www.thomas-krenn.com/en/wiki/Installing_Intel_Network_Card_Drivers_under_Debian

 

[Goggel]

The latest driver version for my network cards is version 5.4.6 according to Intel. Intel® Network Adapter Driver for 82575/6, 82580, I350, and I210/211-Based Gigabit Network Connections for Linux*
Is this driver present in latest version of Proxmox ? If not.
Can I install the driver myself ? If so. How.

 

[Goggel]

After installing Proxmox on my desktop PC I can conform that there is no problem with the network cards or with the drivers.
I think I'm having a issue with my Fujitsu server (missing drivers)

 

[Goggel]

Some people advised me to turn TCP offloading off, butt it didn't make a difference.