I have one of these on my backup Server. But about 2 out of 5 times the HDMI signal is not detected (after the Backup Server was running for a couple days) and I need to restart the Backupserver to get it working. restarting the JetKVM does not work. In comparison I had none of these issues with a NanoKVM. I don’t know if it is a problem of the JetKVM or the Backup machine.

You could use a NanoKVM together with tailscale: https://wiki.sipeed.com/hardware/en/kvm/NanoKVM/network/tailscale.html

These cost around 60€ (don’t know the dollar price) on Aliexpress (I remember them being a lot cheaper in the past…).

You do not need to use tailscale on the NanoKVM. You could use whatever VPN tooling your router supports to connect to your network and then to the NanoKVM.

P.S. There was fuzz in the past about them including a small microphone that was not documented. Make of that what you want.

Do you compartmentalize the disks again, or do you just make different folders?

Yes, when you are not using BTRFS. Due to OMV using ext4 as default you basically create your Raid and then folders/networkshares on top of it.

ZFS on the other hand allows you to create datasets which are separate ZFS filesystem object that can have its own settings (quota, reservations, permissions, etc.). The “same” goes for BTRFS which supports BTRFS subvolumes.

I do not know how well OMV supports BTRFS and how well it is integrated in the overall workflow. Therefor I cannot give a recommendation if it is feasible to use BTRFS on OMV.