Since a couple of weeks I can no longer connect to NordVPN, nor get live traffic updates for TomTom while connected to the 4G KPN network. When connected to Vodafone or WiFi everything works just fine. Also when using a KPN Prepaid card, everything works fine. I’ve just inserted a new SIM-card (for the same phone number), yet that doesn’t solve it. Nor swapping SIM cards between slots or re-installing the NordVPN app.
Any suggestions what might cause this?
Solved:
KPN is rolling out IPv6, and apparently I got selected as an IPv6 user a few weeks ago. And it seems that the IPv6 protocol of KPN isn’t fully working with all sites and services.
One can switch off IPv6 in Android. Done that, and everything is solved 
See here how it’s done (scroll down to Android)
Go Settings -> Connections -> Mobile networks -> Access Point Names. Select your mobile operator the scroll down to APN protocol and select it.
Select IPv4.
And you’re done.
Cheers