Fritzbox connected to LAN jack but no Internet?

I live in a student dorm where every room has a LAN socket. Accordingly, I have connected my PC with it for a week. For this I had to register on one side of the dorm. (There you have to register only once to unlock the internet access)

In order to have Internet on my laptop and smartphone, I bought a Fritzbox 4040. The cable, which was included, I put dementscrechend in the socket and on the WAN connection of the Fritz box. The Wi-Fi symbol lights up green, power of course too.

On my phone, the Fritzbox also appears and I have entered the password of the Fritzbox. The wlan icon also appears in full strength in my notification bar. Nevertheless, I have no internet connection. I sent a message about Whatapp, which was not sent accordingly. I simply have no connection.

Did I connect something wrong or do I have to register again? Stop for the Fritzbox?

No, there seems to be another problem: the dorm uses a captive portal. I do not know if that goes with the Fritzbox. You may have to flash your firmware.

For this I had to register on one side of the dorm

What kind of registration?

If it was only the MAC address, it is enough of the frit on the WAN port to enter the MAC of your computer…

You have to set the router correctly.

on the web surface of the Fritzbox under Internet attitudes one must adjust the Internetprovider on LAN1 (Client mode) .dann the LAN cable not in WAN but on LAN1-haven stick, then it should work.

On a page called Netaccess. Just went for my internet access is unlocked. Have already connected my PC via ethernet. But everything works.

Why because of the calculator? The Fritzbox should only be for my smartphone and laptop (primarily smartphone) The PC remains on Ethernet. So at least the plan.