Thank you for the post.
This is the expected behavior as currently designed. FileMaker Server’s test pages use the I.P. address instead of the fully qualified domain name.
If you would like to see a change in this behavior, I would encourage you to enter this as a suggestion into our Feature Requests web form at:
These web form suggestions are monitored and read by our Development and Product Management departments and then discussed and considered for a future release. Although I could copy your post and paste it into the web form, there are some questions asked that only you can answer.