The Persistent Tunnel
Ubuntu utilizes NetworkManager to handle all internet connections. A powerful feature within NetworkManager is the ability to link a specific Wi-Fi or Ethernet profile to a VPN connection. If configured this way, the moment Ubuntu detects you have connected to your local network (for example, your home Wi-Fi), it will automatically attempt to establish the linked VPN tunnel. While excellent for security, this is highly disruptive if the VPN server is currently down (leaving you without internet as Ubuntu repeatedly tries to connect), or if you only need the VPN for specific, occasional tasks and prefer the faster speed of your direct connection for general browsing.
Breaking the Network Link
To regain manual control over your secure tunnels and stop Ubuntu from automatically connecting to a VPN when you join a specific network, you must edit the properties of your base network connection.
Click on the network icon (Wi-Fi or Ethernet) in the top right corner of the Ubuntu top bar. Select Settings (or “Wired/Wi-Fi Settings”). Find the specific network you are connected to (e.g., your home Wi-Fi name) and click the small gear icon next to it to open its properties. In the new window, navigate to the General tab on the left. Look for a checkbox labelled Automatically connect to VPN. If this box is checked, a dropdown menu below it will display the name of the VPN it attempts to use. Click the checkbox to uncheck it. Click the green Apply button in the top right corner. Ubuntu will now connect to that specific network normally, and you must manually toggle your VPN on only when you need it.