Session problem

I have a problem with the empiremt2.it site
In short, the script I use must have a unique ip.
When it changes ip, it automatically throws you out.

This happens in the login and administration module.
Now I don’t know what to do to solve the problem.
I tried to add part of the line code to session_id
but when it seems it does not give the desired results.
My idea would be to do a general include of the script and add the code part.
Could you give me a hand?

Thank you