[SOLVED] Help! .My 1 Gigabit Connection working only one way. Why ?

[Proxmoxbeginner30]

Hello to all network experts,
my Proxmox Host 7.3.3 reaches in the Iperf3 test only full 1,09Gbytes when I start the iperf3 from the client, in the other direction only 95 Mbytes.
What could be the reason for this?

I already changed cables, same result!
Network settings checked everything ok, both have MTU 9000
VM to client the same problem, in the other direction everything fine.

My hardware:
Xeon E5 2630 LGA 2011
16 GB RAM Samsung DDR3
Server Mainboard China 2011
3x Crucial SSD
2x WD RED Plus 4 TB are mounted in my VM
Kernel: 5.19.17.1

Client as Iperf3 Server and Proxmox Host as Client WORKS!

Now it works again with Cat5E