Closed Joining server via "internet ip" wont work

Ok so I played Starbound together with friends before Furious Koala but now I'm having quite some strange issues. I can join my server by using 127.0.0.1 without any problems but when using my "internet ip" and clicking join, starbound freezes for like 15 seconds and then the error you can see in the image shows up, my server on the other hand gives me another error (see the image ).. The line starting with "Warn: I/O Error" partially is in german (I guess because my os language is german..) but it essentially translates into "a connection attempt failed because the connected host didnt respond".

It seems like both sides want to tell me the other site didn't react which is kind of ridiculous.. I forwarded the port 21025 and according to this website (http://www.yougetsignal.com/tools/open-ports/) it is open.. I searched for answers on google as well but it seems that nobody has this particular problem I have.

 

There is nothing wrong if yougetsignal detects it opens and you can connect 127.0.0.1. You cannot connect yourself your internet ip this is a general rule ..

 

I am sorry then I did not know this! I am well aware of the fact that everything was set up correctly it just is completely new to me that I cant connect to my computer via internet ip!