I have setup 2 UCS 4.3 servers (both migrated from 4.2). First one is PDC with Univention Virtual Machine Manager, the second one is a UCS member server and hosting KVM.
When I create a new VM via UVMM on the KVM host I cannot access this VM from the network. The VM can access the network without problems. I have tested with Windows 10 Pro and LinuxMint 18 VM Guest.
Network setup of the VM is briged to br0.
The VM has its own IP on the subnet. I can ping the IP. But all other services do not respond.
From the KVM host I can SSH into the Linux VM. I have checked the fingerprint to verify I am really on the VM.
Disabling firewalls on host and/or guest did not have any effect. Neither on Linux nor Windows.
Therefor I assume that KVM nwfilter might not be configured correctly.
I have invested 2 full days on investigation already and I am somewhat desperate now.