Yesterday I assigned a pc to a profile.

There's a limit of 12 hours of use in this profile. I can see the message saying that the limit has been reached, so this pc has no internet connection.

Ok.

Now I need this pc to be connected again to internet.

1- Tried to add a new profile without any limitations, and then assign this pc to this new profile. Still no connection to internet.

2- Tried to remove the pc from any profile. Now the pc has no profile assigned. Still no connection to internet.

3- Tried to reboot the pc. Still no connection to internet. Message in browser is: "Restricciones de Control parental. No tiene permitido navegar en la red en este momento. Puede volver a conectarse cuando el Horario de Dormir haya acabado", which can be translated to something like "Parent control restrictions. You are not allowed to browse the net(internet). You can connect again when sleep schedule is over". This pc is no longer assigned to any profile, so this message should not be displayed and internet should be available.

Just in case: of course internet is working fine, other mac/pc are working fine with internet connection. 

How can I restore the internet connection in this pc?

IT SEEMS TO BE A BUG.

Edit: more info added.

Edit2: disconnected ethernet cable cat6, tried connecting using wifi (slower speed of course...) and now the pc has internet. Disconnect wifi and connect ethernet cable again => no internet again.