https://docs.syncthing.net/intro/getting-started.html#getting-started

Syncthing was installed with `sudo apt install syncthing` after all packages and lists were updated.

TCP port 8384 was allowed through the firewall with:
```
iptables -I INPUT 1 -i enX0 -p tcp --dport 8384 -j ACCEPT
```

You can validate which ports are open with `iptables -L`