#SyncThing doesn't work on my old galaxy s5.
Probably an old 32-bit CPU is the problem or insufficient RAM...
But at first start it took about 20 minutes to generate keys, and after I've added 3 devices and about 5 folders, half of them just disappeared from lists.
Like I've added my PC, another phone and laptop, closed and reopened the app and saw only my PC :D
And the same with folders, one was there, but others were just ignored despite I saved them correctly.
So, it seems like this phone is too old to use it as a backup device for SyncThing. Sad but not fatal.
I'll look for another way to sync my audio books from PC and keep their progress.