Cannot connect to Local Web Server via Public IP

I have the device with Web Server connection for Configuration.

I have set port forward in router to connect the device via Public IP (or Dynamic DNS) The port i've set is 80 (HTML)

When i connect via Public IP (Ex: 1.55.154.185:80), it works, but only in the same LAN. When i connect from other Lan is does not work.

I try to creat the Web server using Xampp to test ==> it works normally whether it is the same LAN or not

How can i handle this issue? In case of web server of the device is not support, can i use the intermediate web server to do this?

Thank you