I need a better way to study my CCNA material.

I'm in school for the first time since being diagnosed with ADHD a few years ago. I'm a self-taught beginner programmer and I got through that with hands-on projects which kept me focused. But, I'm currently taking a 4-course CCNA series at a community college and it's mostly reading on my own with an in-class review(kind of). The professor for the first two classes (it will be a different one for the next two) didn't really delve deep into the topics in class and I felt like it was up to me to teach myself. I passed both classes with A's but the material was really dry and took me hours, sometimes days, to read the chapters. I took notes while reading but I don't think I was being efficient about it and it felt more like I was memorizing to pass a test rather than actually understanding concepts. Last semester those were the only classes I was taking but Spring semester I'll be taking two additional classes and can't be spending so many hours reading for one course. Does anyone have tips on how to study this particular material more effectively? I am interested in what I'm learning but my brain just won't cooperate.