Over the past few years, being able to connect to airport Wi-Fi seemed to be luck of the draw. Sometimes it worked, sometimes it didn’t. The most frustrating was that I could never have the modal window to sign in to the Wi-Fi network.

So what was the solution? I found that using custom DNS settings—I use Cloudflare’s 1.1.1.1 and 1.0.0.1—were the cause of the problem. Deleting those while I am travelling is the solution, and maybe it can help some of you as well.

I asked ChatGPT to explain to me why that is the case, and this was the answer:

The window that appears when connecting to public Wi-Fi networks, prompting users to log in or accept terms, is commonly referred to as a “captive portal.” This portal intercepts network traffic until the user interacts with it, ensuring compliance with the network’s requirements.

Captive portals function by intercepting HTTP requests and redirecting them to a specific login page. However, using custom DNS settings, such as Cloudflare’s 1.1.1.1 and 1.0.0.1, can interfere with this process. These DNS settings may bypass the network’s DNS servers, preventing the redirection to the captive portal and causing the login page not to appear.

To resolve this issue, it’s advisable to revert to the network’s default DNS settings when connecting to public Wi-Fi networks. This allows the captive portal to function correctly, enabling proper access to the internet.

Custom DNS? This article explains why to do that.