The ProtonVPN Windows app and our Linux command line tool allow you to use two different transmission protocols depending on your situation. This article explains when to use each protocol and how to switch between them.
ProtonVPN uses the OpenVPN VPN protocol, which supports the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP). These two protocols determine how the packets of data that make up your online traffic are sent from your device to the VPN server.
There are several technical differences between UDP and TCP, but, broadly speaking, UDP supports faster connections while TCP supports more stable connections and is harder for governments or network administrators to block. The Linux command line tool uses the UDP protocol by default, while the Windows app uses auto protocol selection. Unless you have a reason to change protocols, we recommend you leave the default settings alone.
Learn more: What’s the difference between UDP and TCP?
Use UDP if:
- Your online activity requires a fast connection, like streaming films, playing video games, or sharing files over a P2P network.
Use TCP if:
- You are in an area with a weak or unreliable WiFi signal.
- You are on a network that you suspect blocks VPNs (e.g., a country where the Internet is censored, a university WiFi network, etc.).
Smart protocol selection
For versions 1.9.2 and later, the default protocol option for the ProtonVPN Windows app is smart protocol selection. When this feature is enabled, the ProtonVPN app first attempts to connect using UDP. If the app detects that your connection is blocked, it will automatically switch from UDP to TCP and try to connect again. The app also automatically scans the network to discover and use the port that offers the best performance.
Changing protocols manually
If you would like to change VPN protocols, please follow these steps:
- Open the ProtonVPN app
- Go to Settings
- Locate ‘Default protocol
- Select the preferred VPN protocol you would like to use to connect
- That is it! Now you will connect to the VPN using your preferred protocol.