Hi all, 
It was really bothering my how I had to change networks on my phone just to sync my Syncthing files, and having to check what new IP I had to connect using something like Filebrowser plugin was a lot of steps, so I fixed both of these in one with a koreader plugin for Tailscale VPN that can slot right into your Syncthing setup.
Repo here: [
koreader-tailscale]
- Always-Reachable Device: Your e-reader gets a permanent Tailscale IP, even on different Wi-Fi networks (e.g., home/work/café).
- No Hassle: Tailscale bypasses NAT traversal issues, so Syncthing/SSH/etc just works anywhere
How it works
Full instructions on repo but in short:
1. Set up a Tailscale account, we'll need a key shortly.
2. Download the plugin from the repo 
3. Copy plugin to KOReader’s `plugins` folder.
4. Make a key and move it to `/mnt/us/tailscale/bin/`
5. Run the install script on your device (installs arm32 binaries for Tailscale, only tested on Kindle PW6, but I think this should work on anything on that platform? Or can work with script tweaks or 
manual binary install)
For Syncthing, you want to use the tailscale IPs in Addresses:
`tcp://tailscaleip:port`
For anyone who wants less hassle with remote access to their KOReader device (e.g., for backups or file transfers).
Give it a try and let me know how it works for you! Feedback and contributions welcome.
Fair credit to mitanshu7's 
[tailscale_kual], this is essentially that but on UI/instruction steroids, and with a script to install the binaries.
This is as-is for now, but I'm trying to decide if there's anything else worthwhile to implement here that wouldn't be better as a contribution to either the SSH or Syncthing plugins, both are excellent and play extremely nice with this!