I had to look it up what is mean. The following is correct? “hairpin NAT allows you to run a server inside your network but address it as if you were outside your network”
The Ubuntu machine that has default a loopback interface installed. Not sure how now to solve NAT hairpin/loopback issue. A solution that I found was created DNS override?. I did found this post and double check all the suggestions. Do you have any idea what to check to resolve this?