@Lrd_Netrox953 Short answer: you can’t.
As far as I know, servers stay active all the while there is a human in it.
Once there are no humans in it, it will close down.
This is what I have been led to believe anyway.
There is word that they are hinting they will add persistent servers at some point, which will remain open.
But I am having my own issues with hosting servers right now.
Portal is seriously screwed since the last update.
https://answers.ea.com/t5/Battlefield-Portal/Unable-to-take-down-server/m-p/11881150#M1330 
