My company uses the same domain internally and externally. The internal Windows domain is mycompnay.com and the company’s public website is www.mycompany.com
A WWW A record on the internal Windows DNS server points to the public IP of the hosting server to allow staff to access the public website.
Both internal and external users can access HTTPS:\\www.mycompany.com.au
However, when internal clients try to access https:\\www.retailfirst.com.au\wp-conten\
a certificate error occurs – NET::ERR_CERT_AUTHORITY_IN
VALID (External users do not have this problem).
If I change an internal PC to use DNS 18.104.22.168 (Goodle DNS) all works fine.
I think this is related to mycompany.com.au resolving to an internal private IP when accessed from an internal PC and resolving to the public IP of the hosting server when accessed from an external PC.
Attached are the certificates returned when accessed internally and externally.