Step 1 – Add Syncthing repo to apt sources

echo "deb syncthing stable" | sudo tee /etc/apt/sources.list.d

Step 2 – Add Syncthing’s PGP keys

curl -s | sudo apt-key add -

Step 3 – Update apt’s database and install

sudo apt update
sudo apt install syncthing

Step 4 – Enable the Syncthing service

sudo systemctl enable syncthing@username.service
sudo systemctl start syncthing@username.service