Fiber activated, but no internet: Experia Box gets no connection

I am a KPN customer and I am moving from DSL to fiber. My DSL connection still works. The fiber does not work yet.

Timeline
- 5 November 2026: I received the Nokia fiber box (ONT) from KPN and connected it. The Connection light was steady, but there was no internet. I expected this, because the activation was planned for 6 November.
- 6 November 2026: I received the email that my fiber is activated. I followed the installation steps on the KPN website. The last step says: "Oeps, we zien dat je nog niet bent aangesloten. We gaan proberen je verder te helpen."

Current status of the fiber box
- Power: on
- Connection: steady
- Data: blinks now and then but mostly steady
- Alarm: off

After a restart, the Connection light first blinked very fast for a few minutes and then became steady again.

What I tried
- I connected the fiber box to the WAN port of my KPN Experia Box v10 and removed the DSL cable.
- The Experia Box detects the fiber box, but it gets no internet connection. In its status, it switches every 30 seconds between "PPP connecting" and "DHCP selecting", and it never gets an IP address.
- I restarted the fiber box and the Experia Box, more than once and at different times during the day. Nothing changed.
- I checked the cables. The fiber cable is clicked in.
- When I connect the DSL cable again, the Experia Box goes back to DSL and the internet works.

I could not reach customer service by phone, and the activation email is from a noreply address.

Question: can a moderator please check whether the internet service is set up on my fiber line and on this fiber box?

Thank you!