Cisco websites

[Panja 2]

Any website related to Cisco cannot be accessed when connected to Dutch AirVPN servers.

For instance:
https://cisco.com/
https://www.cisco.com/
https://community.cisco.com/

I'm using Unbound for recursive DNS and over VPN I do not get an answer.
When using 9.9.9.9 I do get an IP back when doing a lookup.
But once I change my DNS to 9.9.9.9 I'm still not able to access the websites.