Aion Private server Downgrade

Hello everyone

Hello im new in this so i actually hope to find some help here..

So i got a big problem

Im trying to make my Own Private server to Bring it Online later on when everything is ready. Its called Aion OldShool 2.5

The problem is now i diden't find any guide that helps me how to set up a PTS version 2.5 .
The best guide i could find was on youtube Making a Pts version 3.9 .

So i did that ...
Now i wondering how to downgrade it to run these game/login server files on the 2.5 server. I Already have Aion version 2.5.

All help is welcome.

Skype: Willievvartaal:mofo:

its possible to downgrade but it will take much time ! you need old opcodes and the old packet structure have fun