Hello I'm having similar problems.. Just re-edited this post since at first i thought it was restart to the TVH process, but in fact it is happening after restart to the server (as you had mentioned).
It happens after every restart of the Synology server.
I lose almost 80% of my channels and configurations, and in fact it just happened again after me spending 1 week configuring all my channels and epg and icons etc :-(
Also worth mentioning that the 20% of channels and configuration that remains is always the exact same each time i restart the Synology server.
It seems it's grabbing some previously stored configuration and not the currently updated configuration.
Any help on this issue would be great.
TVH version 4.3.28042017 running on Synology DS2415+ DSM version 6.1.3 (latest)
In the meantime while we await a solution, it's interesting to note that I saved the TVH working configuration directory away (in my case /volume2/@appstore/tvheadend-testing/var, but normally it is on volume1 by default) and restored that after the restart, restarted the process and my configuration changes remained intact.
So something is causing the configuration data to be removed following a restart to the NAS.
To help you out of your immediate issue, you can backup your TVH config directory via tar command and then restore it after the restart to the NAS.
example:
before restarting the NAS:
login to your synology as root user via SSH.
cd /volume1/@ppstore/tvheadend-testing
tar cvf config_backup.tar var
restore after restarting the NAS:
login to your synology as root user via SSH.
cd /volume1/@ppstore/tvheadend-testing
tar xvf config_backup.tar
you can then use the GUI to stop/start the process again.
Your config changes should now be back again.
Note: make sure to restart your tv clients too at this stage, so that they get the updated info.
BR
Stewart