You must have the protonvpn-cli installed (the official one, not the community version).
[Unit]
Description=Connect to protonvpn, fastest server, after user login
After=graphical-session.target
[Service]
Type=simple
ExecStart=protonvpn-cli connect –fastest
[Install]
WantedBy=graphical-session.target
Create this script with: nano ~/.config/systemd/user/protonvpn_start_on_login.service
Then run: systemctl –user enable protonvpn_start_on_login
Then check the status of the script after you log in (should say ”connected to server #X”): systemctl –user status protonvpn_start_on_login
Källa: