Some internetnet provides cannot resolve shift8 DNS

I recently setup shiftCDN
I had a portion of our users call me to tell me the site wasn’t loading.
I discovered they could not see anything that was on the CDN.
Interesting enough I have another site that also uses shift CDN and that one has no problems with the same users.
All of the users that were having problem came from the same major internet provider.

Which ISP are we talking about? Can you provide the DNS servers they are using that is not able to resolve the hostname?

We use AWS route53 for our Geo DNS resolution but I would need to see and repeat the problem to rule out other causes.

Most common cause for problems is web hosts blocking the fetch requests thinking it is automated bot traffic.

I had 2 zones, It only blocked the first zone, not the second. This was one of the major providers.
I’m going to delete the zone and try again.