This step is a theory that many people put out there as a reason for the rise in autism. While there isn't any evidence of a normal amount of internet or screen time being linked to autism (less than two hours a day), there is a link with "problematic internet usage" and worsening ASD symptoms [46,47].

What this means is that if your child has ASD symptoms, then it's best to keep their screen time to a minimum. "Problematic Internet Usage" leaves a grey area of what that specifically means, but I take it to mean multiple hours of screen time a day.
It seems that this isn't just good advice for children with autism, but rather everyone in general (like most things in this guide). Too much internet usage can lead to abnormalities in the dopaminergic system (the system that produces dopamine in our body) and increases our sympathetic nervous activity [48].
What this means is that too much internet use leads to addiction problems because of how it affects our dopamine products along with increasing feelings of anxiousness and stress due to our heightened sympathetic nervous activity.
That's not good for anyone, but to pile that onto everything else our children, autistic or not, are dealing with, it's good advice to reduce screen time. With this, think about every screen you see daily. Your smartphone, tablet, the TV, your child's phone, the computer, and their video games are all screens that add up to this.
Instead of screens, get them outdoors to play in some dirt!