Ankle Dorsiflexion Improvement?

Hi. 

I have limited ankle dorsiflexion, and I'm looking for a way to improve. 

I've tried spending a lot of time in squats with my heels raised on books, with no improvements. I've also tried standing on stairs with my heels off the back, as well as putting my forefoot.

Does Gymnastic bodies have a way of addressing this issue?

Thanks. 

Several of the mobility exercises in F1 SLS progression and many stretches in the Front Split series have got you covered