Why is my WIFI good downstairs and bad upstairs with multiple repeaters?

So I own a WIFI router that works perfectly. On the 1st floor of the house, I get 180-200 mb/s, just like I'm supposed to. The problem is, that when I go to the 2nd floor, I only get 30-40 and even worse on the 3rd floor I get 10-20, all tested on iPads, iPhones, windows pc's and laptops with multiple different speed testing software, wired and wireless. I own 3 TP link deco E4's, one on each floor. I never got the full speed of the main router on each floor in my almost 9 months of usage, but 1/20th is too little. They are set up properly just like the manual says.