Are you starting the server and laptop Syncthings as systemd user units? You'll see stuff asking for 'systemctl status syncthing@yourusername' if you are. That way it works (and has worked for years now) for me. I've kept the config really simple because I only have it syncing at home, so no encryption or discovery. If you also only have it working on a trusted network, maybe ditch the complications...?
The Android side is tough because of all the restrictions. I'd imagine that's what is troubling your phone Syncthing.
Whatever you end up using, have JACK sync 'em up. I used to have two Macs, one for recording with Nuendo and one for doing MIDI sequencing and programming. They synced via MIDI sync and there was always issues. Now I have everything on one Linux machine (Ardour records and mixes, Reaper sequences MIDI and Renoise does beats and other sampling related stuff) and with JACK the sync is seamless <3