How To Make Props and Entities Permanent?

Hello, I was wonder how would you make a entities (ex: MX Radio), or (PlayX) to stay permanent after a restart of the server? (Please explain indepth on how implement this into lua,etc…)

Spawn it in desired area, position it, hold ‘C’, right click on prop/entity,click Persist

That doesn’t work at all. :confused:

Try this it may work (Written in gmod 12)