Quad9 is not as fast as my own ISP, so back to Ziggo.
Trying the new AdGuard extension.
I spoke with Quad9 about some routing issues. Their speed wasn’t bad for name resolution, but not all their servers are setup for transit, and your ISP may route you elsewhere based on their network optimization. This causes issues with getting CDNs close to you, I was being routed halfway across the country to Chicago. Which was fine for DNS queries, but awful for getting CDNs based on the DNS server location half way across the US (a long way). I tried their EDNS Client Subnet, which helps with some CDNs, but others only accept edns info from Google or OpenDNS as they have agreements about how to handle the location data safely/privately. So, results were mostly good, but family streaming services buffered. Also their DoT implementation has a higher rate of failed requests.
All of this to say they responded quickly and worked with me to troubleshoot. The couldn’t fix the problem since they have no agreement with my ISP, but they are working on implementing more servers for transit to help alleviate these issues. And their “customer service” is fantastic! They were friendly, prompt, and helpful. Quad9 is an amazing not for profit, but for now we also went back to my ISP. It is lightning fast and have CDN caches in their edge services that you can’t beat the performance.
Sorry for the long winded post in your wall, but I really like Quad9 even if I don’t use them either.