I am not here to disparage Syncthing developers and support group. On the contrary, I am still very impressed with ST process. I am here to tell my story if it helps. Please don’t read this and feel badly about your work.
TLDR: I tried SyncThing, but I settled on rsync.
I came to Syncthing on recommendation of Steve Gibson’s recent podcast on TWIT Security Now about his quest for synchronization. I setup ST syncs for my laptop and TV computer basic folders and one to sync my Music folder from the TV computer to the old Synology (DS212j). I had some limited experience with rsync and luckyBackup, both of which were negative. My Music folder changes only occasionally as I add new CDs to my collection. I rip them to the TV computer and then ST them over to the Synology. They are simply folders with FLAC, MP3, and graphic files. I use Subsonic to serve music from the Syno with DSub on my phone and a web browser on the TV. I use Airsonic on the TV computer in hopes that it might someday address the shortcomings of Subsonic.
ST never seems to be able to sync the Music folders, whether they are one-way and esp. if they are bi-directional. There are always a handful of folders that won’t sync. Even the home folder syncs on my laptop always had issues with unsyncable folders or folders that changed too often and I had to put ignores on. (I wish Mozilla would address the issue of directories for backup versus directories for holding ephemeral state, but they have their own defective sync product that I now use instead of ST.) ST slows the old Syno to a crawl making it impossible to use the Subsonic server.
So I spent a few more days studying and experimenting with rsync and I finally understand enough to make it work for my Music folder. It is a marvel of speed and efficiency with only two lines of script to do a dry-run followed by an actual. Anything goes wrong, there is understandable output to diagnose. I can set permissions how I please, but I can’t yet do any ignores or matching, but I don’t need that complexity. I don’t do deletes. It’s safe and easy to understand. Thanks for listening.