If you have used a Vodafone device as a portable Wi-Fi hot spot for your Mac, then you might encounter continual requests to log in to a Vodafone mobile Web site whenever you attempt to connect to the Internet using your standard network.
When this happens, opening Safari or another browser will result in the system attempting to connect to the address "http://vodafonemobile.wifi/" and present you with a log-in prompt. Efforts such as clearing network ports, setting up new network locations, and removing preferred Wi-Fi networks will likely not help the situation.
The problem here is that Vodafone devices install a background service and alter your system to override many of the manually configurable network settings, and make the Vodafone device the preferred network for your system. When the device is in range and properly configured for user, the connection will be seamless; however, when you are not on the same network then the connection will fail, and in some cases the configuration may trigger the browser window with the log-in prompt.
To undo this change, you will have to uninstall the Vodafone software on your computer. First check the Applications folder for a Vodafone Utilities directory, in which you should find an uninstaller tool that can be run to remove the software. Alternatively, if you still have access to the Vodafone device then you can attach it to your computer and browse it for an uninstaller.
If your system does not have an uninstaller, then try reinstalling the latest Vodafone software and then access the uninstaller it provides and use that to remove it from the system.