Cant connect to Internet over a guest wifi of a friends fritzbox

When I want to connect to the Internet over a guest wifi of a friend's fritzbox, I can connect to the guest wifi, but have no access to the Internet.

Adding a bypass rule for the fritzbox ip which is show at the "you have to logon"-screen of the fritzbox-guest-wifi has no effect.

On the guest wifi of another friend's fritzbox where is no logon-screen shown when connecting, I have no problems.

What do I have to do?