I'm currently on vacation in a hotel.
There's free Wi-Fi, but you get to a login page where you just have to agree to the terms of use to access the Wi-Fi.
This works perfectly on the mobile phone, but this login page does not appear on the laptop.
Do you know how I can fix that?
Deactivate your antivirus software briefly for test purposes. These "login pages" are so-called "walled gardens". Your smartphone and laptop want to load a website, but the hotel's router redirects unregistered devices to another website (the login page). Your virus scanner could interpret this as hijacking and block it.
Try a different browser if you have another one on the laptop would also be an option.
In the worst case, connect to Wi-Fi on your smartphone, activate tethering on your smartphone, and connect your laptop to your smartphone. Then your smartphone serves as an access point for your laptop.
