Do you have a stable Kodi + TV HAT system?

Last Christmas I was given a TV HAT and have been struggling all year to build a system that will reliably decode TV. There must be some configuration I’m getting wrong somewhere, so please help!

I have mainly been using a specific Pi3B+ but have also tried other Pi3B+’s and a Pi4, also a second TV HAT and multiple PSUs, hence I don’t think there is an issue with the hardware or horsepower. I always change the video memory to be 256 or 384Mbytes.

I have tried using Raspbian+Kodi, LibreElec and OSMC but none of them seem reliable. I have always been using TVHeadend as the backend.

I can easily set up TVH to tune to all of the muxes available in my area and select programs to be recorded ok via the broadcast guide data. I can set up Kodi to use TVH and get the correct channel list and guide data. I can tune to broadcast channels (both SD and HD).

Where I start having issues is the long term stability of the system. If I tune to a channel and then leave the Pi alone (turning off the TV), the Pi will stop decoding the channel anywhere between 3 hours and 3 days later. Sometimes the system will crash completely, else it may just stop decoding (freeze frame) and perhaps start up again some time later.

Does anyone have a stable system that will decode live TV for hours/days? If so, how did you manage it??

I was aiming to use OSMC (preferably, else Raspbian+Kodi) as a replacement for my aging PVR, with a second Pi adding another tuner for dual decoding capability (a Pi0 networking to the first Pi over USB). But I can’t do that until I am satisfied that the system is reliable, obviously.

A few things that I have tried are:

• In the TVH Config -> Stream -> Stream Profiles, set “Restart on
  error” for htsp and pass
• In raspi-config, select GL2 Fake KMS graphics driver
• Set Kodi to use PLL to maintain AV sync
• Explicitly set the memory cache size used by Kodi in
  advancedsettings.xml

Any help appreciated.