Proxmox IPv6-Only Hosts: Console Issues

When using Proxmox nodes that are only reachable via IPv6 (without an IPv4 address), VM consoles may fail to open while all other functionality works normally.

Opening the console results in a "Connecting..." message for a few seconds, followed by "The connection has been closed". The Proxmox node logs show "TASK ERROR: connection timed out".

Cause

Proxmox only binds VNC connections on IPv4, not on IPv6. This is a known Proxmox issue.

When Tenantos attempts to connect to the VNC server on an IPv6-only Proxmox host, the connection times out because the VNC server is not listening on IPv6.

The Tenantos logs located at /var/www/html/storage/logs/novnc_current.log will show connection timeout errors:

127.0.0.1 - - [23/Feb/2025 18:20:35] Failed to connect to xxx:5900: [Errno 110] Connection timed out

Running netstat -lntu on the Proxmox host confirms that VNC (port 5900) is only bound to IPv4 (0.0.0.0), not to IPv6:

tcp        0      0 0.0.0.0:5900            0.0.0.0:*               LISTEN

This issue has been reported on the Proxmox mailing list but remains unresolved.

Solution

Add an IPv4 address to the Proxmox node's domain name. Once the domain resolves to both IPv4 and IPv6 addresses, the console will work correctly as Tenantos can connect via IPv4.

This is not a Tenantos issue but a limitation in Proxmox's VNC implementation.