WOOHOOO!!!
It does work, fi-na-fucking-ly!
Only, it is still the original IP I have to type in, that one: 46.228.198.108 - LOL!
I guess the 1.2 version of ALiVE makes this finally possible or my rented server provider has changed something regarding internal and external IP after I sent them my error reports as well. I did exactly the same as in all that failed tests before, only now it works.
Another thing I noticed in general also while playing this today and even while playing ALiVE mod-heavy missions hosted on my own PC after the release of ALiVE 1.2 as substitute as long as this issue here was not solved, and hats off to that, is a slight performance increase across the bank. The saving process definitely is faster than in previous versions.
Thank you for your dedication in improving the code of that awesome mod, and thank you for your patience and helpful advice in this thread and others like it!