Can I suggest you try a month cold Turkey with no internet or smartphone. This cured my “ADHD”. I could read programming books cover to cover like it was the lord of the rings after that month.
I don't think you had ADHD, I think you just had short attention-span from social network addiction.
I could not sit down to read a programming book even before smartphones were a thing, I would end up doodling on the margins, or staring out the window for hours.
The only way I could actually sit and learn something was when an external force set a hard deadline, setting own deadlines did not work either.
I now thrive in companies where I have a personal interest in the product or the tech used and have hard deadlines that push me to try to deliver (I might still miss them but I do a lot better than without them). I have learned and been more productive in a 2week crunch than in years. althought it comes at the cost of frequent burnout.