Connected to router, but no internet connection

I know that there are a lot of questions like this here, but I would be very thankful if some one here would help me :)

So, like the question says it, I just moved to a new apartment during college and I tried setting up the internet connection.
For the modem I'm using a TP-Link and for the router I am using a D-link router (which is only g)
When I go to 192.168.0.1. I configure the pasword to WPA (the router doesn't support WPA-2).
And then it says I'm connected to the router, but there is no internet connection.
I connected the modem and router properly. The ethernet cable goes to the WAN port on the router (there are additionally 4 other ports)

I have written everything down that I know, and it still doesn't work, if you need any additional info, just ask :)