14.04 – Ubuntu Server is not accessible over the Internet

My Linaro Ubuntu server is not accessible over the Internet
I have a static IP from my ISP.

I want to diagnose what goes wrong.

The Ubuntu server is connected to my router (Asus RT-N12D1) as well as other Windows 10 Pro computers (it's my PC).

On the router I made the regular ISP setting and port forwarding for the HTTP protocol, as you can see in the following screenshot. Please note that the source destination IP (my external static IP) is hidden by *** characters for security reasons. There are indeed regular static IPs that I can see on different "what is my ip" services.
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At the moment I want to install the LAMP server, adapt and make accessible via the Internet. But unfortunately I have apache2, php, mysql installed and as far as I understand it works only apache2 and only if I call server with local home network over the local ip 192.168.1.55
SSH connection also over local IP works fine.