Server don't works properly

[EtcabezonMC]

Hi everyone!

I have a problem with the server, and this is I can not go on with the external IP address (168.xxx.xxx.xxx, for example) but with the local IP address if I can. The port 25565 is opened successfully, I checked this with programs like PFPortCheker and other Minecraft servers (both with mods and without). 

The server.properties file is correctly configured, this as in other servers. 

I want to play with friends with this modpack because this is the only one that runs well on my computer. 

My ISP is Speedy (Telefonica Argentina), this will add if there is a problem known with this service provider.

 

 

Greetings!