I just wanted to give a feedback that the issue is resolved. Though I found the final solution by myself, Veeam Support was extremely helpful to analyse the issue and point me to the right direction. A very big compliment for the professional work.
Finally the issue was not a software problem of Veeam itself. Deep analysis with wireshark showed that the server was sending RST packages on port 10001 which closed the connection to the clients. The root cause was unclear for a long time.
Updates of drivers, NIC firmware etc. did not help. After disabling more and more things we made it work by removing the virtual Hyper-V switch sitting on the network interface. Hyper-V role is enabled on the VBR server for having more restore and SureBackup options. Interestingly the issue first did not reappear after recreating the virtual switch. It needed a reboot of the server and then the issue was back. This made me mad.
Then I stumbled over some sites describing issues with Qlogic NICs and Virtual Machine Queues. Your find some information here
. Those reports did not fit well because they reffer to VMs loosing connectivity and 1-gig NICs. Our NICs are 10-gig but from Qlogic. So I thought I give it a try. I disabled VMQ on all interfaces using PowerShell.
- Code: Select all
Set-NetAdapterVmq -Name NIC1,NIC2 -Enabled $False
Since then the issue is gone and all endpoint backups work like a charm.
Hopefully this will help someone in the future.