Proxmox VE 8.0 + UDM Pro clients disconnected alerts

New Member
Jul 31, 2023
Hi, I'm having this annoying problem. I installed Proxmox 8.0 on a PowerEdge R250 Server with two NICs. Currently Proxmox is installed using only one of the two cards in bridge with ip

auto lo
iface lo inet loopback

iface eno8303 inet manual

iface eno8403 inet manual

auto vmbr0
iface vmbr0 inet static
bridge-ports eno8303
bridge-stp off
bridge-fd 0

iface idrac inet manual

I have installed some Windows Server 2022 virtual machines (,, etc.) and two Linux machines (Debian 12 and Fedora Server) using VirtIO para-virtualized as network model.

The QEMU agent is installed in every machines.

My infrastructure is: UDM Pro as gateway + 48 ports Pro switch and 24 ports POE Pro switch connected in fiber optics.

My problem is: Dell server with Proxmox and virtual machines are configured to use VLAN 20 called "Servers".

I have not enabled VLAN support on Proxmox's network. I tagged the port with VLAN 20 into the 48 port switch.

The problem is that I get a lot of alerts like the following:
Machine X has disconnected from VLAN Servers. If this is unexpected, please ensure the device's connections are secure and undamaged.
Machine Y has disconnected from VLAN Servers. If this is unexpected, please ensure the device's connections are secure and undamaged.
etc. etc. 1000 times a day.

If I ping from Proxmox to UDM Pro there is no packet loss, same from Promox to UDM pro. If I connect with RDP to a machine I don't loose the connection, but If I log out the machines I get the alert the the system was disconnected from the VLAN.

If I connect to the machines with remote desktop I don't riceve the alert (I left the session active for 10 hours), but when I exit the remote desktop I get this disconnected client alert.

With the Fedora Server I haven't problem, with Windows, Debian and Ubuntu yes.

Can you help me? I'm going crazy.. I don't know if the problem is Ubiquiti or some misconfigued Proxmox.

Proxmox is updated with the last packages and kernel.

Thank you,



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