Of course nothing is as easy as it should be, and this is definitely true for installing a DSL connection at home. My previous internet connection was also ADSL, so I thought switching to a new DSL provider would be easy. Yeah sure.
After talking for more than half an hour with the helpdesk, making me go through endless modem settings while I was already convinced it was a line problem, I decided to just open the wall connection to see what is going on there. Apparently every land line (in The Netherlands) has two physical phone lines. Line 1 (red/blue wire pair) and line 2 (orange/white wire pair). The old ADSL connection was configured on line 2, and of course the new one on line 1. No one told me this, so with nothing to lose I decided to switch some wires and move to line 1 (red/blue). This turned out to solve the problem indeed. So, finally ADSL again after using 3G for way to long 🙂
The new Fritz!Box works fine, but takes a very long time to get ADSL line sync. The DrayTek Vigor 120 is much faster (I used this one initially to test my line hacking)… Not sure if this will be a problem in the future, but the Fritz!Box wizard was unable to successfully test the Internet connection after setting it up because the line wasn’t synced yet. Waiting another minute solved that.
Very helpful resource (in Dutch) that explains all about the wiring can be found here.