Root cause here
I found in the logs, that not connected network cards have APIPA IP addresses
In my server I have 6 LANs and only two connected yet the rest 4 left . Veeam server believe those LANa are up and operate regardless of the status down state.
see:
Network Interface, Name: Embedded FlexibleLOM 1 Port 2, Description: HP FlexFabric 10Gb 2-port 554FLR-SFP+ Adapter, Interface Type: Ethernet, Operational Status: Down;
Unicast IPAddresses: fe80::91b5
3cf:69ea%3; 169.254.105.234;
Network Interface, Name: Embedded LOM 1 Port 2, Description: Broadcom NetXtreme Gigabit Ethernet, Interface Type: Ethernet, Operational Status: Down;
Unicast IPAddresses: fe80::f905:cc0:8502:38be%2; 169.254.56.190;
Network Interface, Name: Embedded LOM 1 Port 4, Description: Broadcom NetXtreme Gigabit Ethernet #3, Interface Type: Ethernet, Operational Status: Down;
Unicast IPAddresses: fe80::d9ef:b71f:dccc:d0ca%11; 169.254.208.202;
Network Interface, Name: Embedded LOM 1 Port 3, Description: Broadcom NetXtreme Gigabit Ethernet #4, Interface Type: Ethernet, Operational Status: Down;
Unicast IPAddresses: fe80:
c35a:f529:7518%10; 169.254.117.24;
Network Interface, Name: Embedded FlexibleLOM 1 Port 1, Description: HP FlexFabric 10Gb 2-port 554FLR-SFP+ Adapter #2, Interface Type: Ethernet, Operational Status: Up;
Unicast IPAddresses: fe80::f855:8577
f971%7; 169.254.249.113;
Network Interface, Name: Embedded LOM 1 Port 1, Description: Broadcom NetXtreme Gigabit Ethernet #2, Interface Type: Ethernet, Operational Status: Up;
Unicast IPAddresses: fe80::7cb3:8adf:6442:b8b5%6; 192.168.100.189;
Gateway IPAddresses: 192.168.100.253;
Network Interface, Name: Loopback Pseudo-Interface 1, Description: Software Loopback Interface 1, Interface Type: Loopback, Operational Status: Up;
Unicast IPAddresses: ::1; 127.0.0.1;
Network Interface, Name: isatap.{99BF1CEF-1943-4580-B2C2-4C31C702B32A}, Description: Microsoft ISATAP Adapter, Interface Type: Tunnel, Operational Status: Down;
Unicast IPAddresses: fe80::5efe:192.168.100.189%8;
Network Interface, Name: isatap.{A235E8C3-31AB-4906-A17D-03E928DFDC8C}, Description: Microsoft ISATAP Adapter #2, Interface Type: Tunnel, Operational Status: Down;
Unicast IPAddresses: fe80::5efe:169.254.249.113%4;
UTC offset: 2,00 hours
When i disabled all not connected LAN cards on Windows ProxMox Proxy agent test succeed.
IT IS A BUG.
Veeam dose not lookup for Link down status of LAN cards when proceed a list of available connections info to Veeam server. This fake info passed to Proxy agent, and then agent getting failed.
CASE opened with ID of 07433641 including all of this.