I have exactly the same problem, and after browsering tons of discusion and documents, finally I figure it out!
there is NO use setting .HTACCESS
Redirect /internal https://localhost/internal/
as this page says,
https://httpd.apache.org/docs/1.3/misc/FAQ.html#set-servername
you have to add this line in your httpd.conf:
servername 123.456.789.123(your ip)
BEWARE
servername https://123.456.789.123/
causes a FAILURE……that’s my problem.
