VPN activation blocks Internet access "DNS server not responding

VPN activation blocks Internet access "DNS server not responding"  - if I turn off VPN, I am reconnected to the server and get an Internet connection. I can't get the 2 apps to work together. I tether and/or wi-fi to my cell phone for my connection. Any thoughts?

 

[Edit: Clarified the subject]

Your ISP might be blocking use of a VPN and not allowing you to access their DNS server. You can change to a public DNS server like Google or Cloudflare.

https://www.lifewire.com/free-and-public-dns-servers-2626062