I have no experience on this, but I found this thread which explains it can causes issue:
I’m sharing this in case it helps someone else, because this issue was
extremely hard to diagnose and looked like a Proxmox or kernel problem at first.
Topology
ISP → ONT → Router → ZimaBoard 2 (pfSense)
→ Switch (VLANs)
→ Proxmox VE nodes
- Proxmox VE cluster (2 nodes + qdevice)
- Multiple VLANs
- pfSense used as router/firewall
- Accessing Proxmox via Web UI shell and SSH
Symptoms
- Proxmox Web UI works, but shell disconnects after ~10–15 seconds
- SSH sessions from macOS/Linux also freeze and then...