We have an unusual problem in that BT Internet users using default DNS settings (BT Hub for DNS resolution) are unable to resolve our domain. This fault only affects BT Internet users but is causing some problems with access to our website.
The registrar and DNS host is Namesco who have confirmed they are not experiencing any issues and other domains hosted on the same nameservers do not have this problem.
Oddly, whilst the root domain is not resolvable other records for the domain are. For example when querying with nslookup it is possible to demonstrate the root domain failing to resolve but www., MX records and other A & CNAME records returning an IP address.
To further confuse matters some browsers now utilise DNS-Over-HTTPS which bypasses local DNS so in some instances it works in some browser but not others and so when trying to report this we've often been told the issue is with the webhost, this is definitely not the case.
What is the process for reporting a fault of this nature to BT's network team? I'm not personally a BT Internet customer and have had issues when trying to report to the customer services team.