$ ping forums.thinkbroadband.com
PING forums.thinkbroadband.com.cdn.cloudflare.net (104.20.170.77): 56 data bytes
64 bytes from 104.20.170.77: icmp_seq=0 ttl=57 time=5.620 ms
I’ve set my primary as 9.9.9.9 too and secondary as Cloudflare. It was only after I got the 2nd identical 500 nginx error that I suspected a CDN issue. To be fair they recovered it pretty quicklyUsing Quad9, did not notice the issue until I looked at the family pihole vps.