I moved from XcpNG to proxmox about a year ago and I am happy with the change, in general.
Now, I started to notice in the last 2 or 3 months, every-time I use the console on a VM, regardless of the OS or the GUI. It works for like 30 seconds, then stops responding for 15, then i see a “reconnecting” message, and then I have 30 more seconds of normal operation until it freezes again and repeats the cycle.
This is really annoying and the 1st ting I do after installing the OS is to use SSH or VNC or RDP immediately. This happens regardless of which computer or browser i use to login to proxmox.
As annoying as proxmox is, I never saw that. Check your network connectivity. Leave a ping to proxmox on your pc and leave a ping from the proxmox box to your default gateway (unless that one is running inside proxmox, which would be bad), preferably in a screen session.
It sounds like TCP / HTTP disconnects to me. Maybe from a failing ethernet port, a loose cable, electromagnetic interference or maybe other failing hardware on the proxmox box. I don’t think it’s an issue with the software itself. If novnc had issues, it wouldn’t take 3 months to get fixed.
I’ve never run into that myself, so I wish I could help with that. If you figure it out, be sure to post about it just in case someone else is dealing with it.