The Persistent Connection
Ubuntu’s NetworkManager is designed to be helpful, automatically remembering every Wi-Fi network you successfully connect to. By default, it tags these networks to “connect automatically.” This means if you walk into a coffee shop you visited three years ago, or if you walk past a public library with a known open network, Ubuntu will immediately drop your current cellular tether or secure connection and silently route your traffic through the known Wi-Fi network. This can disrupt active downloads, break VPN tunnels, and expose your traffic to potentially insecure public access points without your explicit consent.
Disabling Auto-Connect for Specific Networks
To retain full control over your routing and stop Ubuntu from automatically reconnecting to specific saved Wi-Fi networks in the background, you must edit the individual connection profiles.
Open the main application launcher and search for Settings. In the left-hand sidebar, click on Wi-Fi. In the main panel, under the “Known Networks” section, you will see a list of every network your computer remembers. Locate the specific network you want to prevent automatic connections to (e.g., “Starbucks WiFi”). Click the Gear icon next to that network’s name. A new configuration window will pop up. Ensure you are on the Details tab. You will see a checkbox explicitly named Connect automatically. Click the box to uncheck it, and then click Apply in the top right corner. Ubuntu will still remember the password for this network, but it will never join it unless you manually click on it in the Wi-Fi menu.