tvheadend

I have a tvheadend LXC on my PVE7 which is (was) working excellent for years. Since a few months I'm expecting "Continuity counter errors" within tvheadend's log after watching or recording live TV for ~10 minutes, which are visible/hearable as hickups, garbage and artefacts in the video and...

Any suggestions on troubleshooting poor network performance when serving media would be much appreciated. I have Linux proxmox 5.4.124-1 running Virtual Environment 6.4-13. Hardware is 12 core Xeon E2-1650 v2 64 GiB ECC RAM. pfSense is the network router/firewall via VM, wireless interface...