Internet fast only for some devices but slow on others

Oct 26, 2019
My wifi is surprisingly slow for my relatives whenever they try to use their laptops and phones but for some reason it's fast for my laptop, phone and decent for my game consoles (Xbox One and PS4) I'm aware that sometimes a Playstation can hog up internet sometimes but I've tested the internet while it's off on my laptop and I've got 57 mb/s (which is close to 60 mbs which is a part of my internet plan) as a result from I also get similar results when its on. but when I try my mom's laptop in the same room it can barely get above half. My Iphone has no trouble at all with it but they constantly complain about theirs being slow. I called my internet provider and they blamed it on my consoles but I have a hard time believing it because whenever it's not on they still complain about it often. Every time we call them they have us test the speed and yet again try to put the blame on something that is not related to the issue.

I can't make any sense of this problem and it's clear my internet providers are not trying to make any effort to help. Is there an easy way to solve this?