Server 2019 QEMU-VM randomly loses network connection

Question

I am facing a problem with a few windows server 2019 machines that run on my Proxmox VE Cluster. They repeadetly lose their network connection and so far, only a restart of the VM solves the problem, just for it to reappear in a few days again.
I already checked the network configuration itself for any errors, not only on the VM but also on the hostmachines (network bridge and physical host seems fine). Causes like IP or MAC duplication are not the case.
The windows boxes do not log any errors inside the event protocol, only a change of the network profile and the following error messages from the applications (AD DC, DNS,...) resulting from the connection loss. I also checked for any concurrent happenings during the time of connection loss, such as windows updates or anything similar but nothing seems to happen.
The "connection loss" includes that i cannot reach the VM from the outside and windows cannot ping the outside. Network shows a "not identified" message. Dis- and re-enabling the network interface through the network center does not solve the problem.

Changing the VM settings inside proxmox, for example from using a virtual e1000 to virtIO and setting a different machine type (currently using q35) have not solved the problem either.
I basically ruled out most of the possibilities that the issue lies within the proxmox Host as i already spend weeks of troubleshooting with the proxmox support. We came to the conclusion that this issue has to be with the windows itself.
Also other VMs on the same hosts, even other windows boxes (for example WIndows 10 or Windows 2016) work without problems. This phenomenon only occurs within Win 2019.

I'm not that much experienced with windows troubleshooting so i apprechiate any kind of help or tips for ways to look further into this.
Thank you in advance for any help.