2009 Macbook Time machine drives not showing.

I have a 2009 Macbook, its not may daily driver but I want to use time machine on it. I recently made a Mac Mini time machine server and it works fine on my 2011 Macbook Pro, but not on my Macbook. By the way the Macbook is running El Capitan while the Macbook Pro and Mac mini are running High Sierra.

MacBook, OS X El Capitan (10.11.6)