NAS having problems reaching certain domain link pages of web server

[Ralphort]

Edited...

 

[sfx2000]

What router is in use?

Some have default settings that make it a challenge to hairpin in from behind the router.

 

[sfx2000]

Asus protects things - and they can get in the way of hairpins...

Hairpin NAT is a useful technique for accessing an internal server using a public IP. Since you are using a public IP/Hostname to attempt to access a server in your network, the traffic will attempt to go out to the internet.

In order to reach the server, the traffic will need to be redirected to the correct location.