Hi ​@doodee 

At KPN, as a consumer you can only have a dynamic IP address, but it hardly ever changes.
However, KPN can change it if necessary for its network setup. You will also receive a new IP address if the "carrier" changes, so if you are converted from copper to fiber.

You can enable an option in MijnKPN  to receive a warning prior to a planned change of the IP address. Go to the privacy settings in the “Profiel” and select your internet subscription.