[SOLVED] In VM, I constantly lose the VNC connection (Console)


May 16, 2020
I launch a VM, for example to configure the Debian installation; I work for some time, but then I lose the connection in VNC console.
My mouse moves, but not the mouse inside the console.
I have to click again, more than one, and wait several seconds to see "Connecting" and go back to an operating console.
This happens both when there is a graphical screen in the console, and when there is a character screen, such as the Linux VM console.
This happens to me all the time; during the last session I counted more than 20 connection losses in less than 10 minutes.
There seems to be some timeout that doesn't check if I'm working in the console.
For example I lost the connection after I finished typing the username and while I was typing the password.
It becomes impossible to work in Proxmox like this.

This is the server information.
CPU (s) 24 x Intel (R) Xeon (R) CPU E5-2620 v2 @ 2.10GHz (2 Sockets)
Kernel Version Linux 5.11.22-5-pve # 1 SMP PVE 5.11.22-10 (Tue, 28 Sep 2021 08:15:41 +0200)
PVE Manager Version pve-manager / 7.0-13 / 7aa7e488

The server memory is 64GB and the problems occurred during the launch of the only VM present with 2 sockets, 2 cores, 2 vcpus, 4GB RAM, ISO for Debian 11 installation.


Proxmox Staff Member
Staff member
Nov 19, 2018

can you reproduce this behavior with other browsers?

have you tried using SPICE? [0]

are you experiencing connection issues otherwise?

does it happen only on this VM?

[0]: https://pve.proxmox.com/wiki/SPICE


May 16, 2020
On the server there is only this VM and after the problems encountered during the installation of Debian 11, I am now encountering them again with the VM started, obviously with Debian server in terminal mode.
The VM started at 15:41:54 and at 15:58:13 I already count 12 interruptions as reported in the Proxmox task list, below.

Tried with Chrome, Opera, Edge and Firefox (All in private mode) and all crash for no reason.
I don't know Spice. I will try to install it.

I don't think it's a browser issue because it reports the VNC console freezing even while I'm not working in the browser.
If I select the "Summary" window and after a few minutes I go to the console again, other blocks that occurred while I was not working on it are reported.

=== Update ===
In my opinion this "timeout" is more a server problem than a console problem.
If I go to Datacenter/Summary, it sometimes takes a few seconds for the screen to refresh.

=== Update 2 ===
Now I have 4 VMs and always the same problem.

If, on the other hand, I am working in the server shell, losing the connection I am forced to reopen it.

Furthermore I didn't understand how to connect with Spice.
I have installed Virt-Viewer on Win10.
Then when I connect with spice: // 8006, I get the error "Could not connect to the graphics server spice: //- 8006"
Last edited:


May 16, 2020
The shell also crashes.
If I comment the lines created for the vmbrs in Interfaces the shell starts working again, but obviously the VMs don't.
I close the post because the problem is with the network configuration. I reopen a separate post.


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