Ask HN: How do I get better at solving issues (while coding)?

I've been hobby coding for 4-5 years (I'm in my early 20s) because I find it fun. Despite being diagnosed with ADD, I recently decided to pursue a SWE degree and it's been intense but fun. I had an exam today and failed it, largely due to inability to solve an issue. In hindsight it was a fairly easy issue, but I'm pretty disappointed in myself. I know the syntax and how it all goes together, it's just the solving part that's so damn hard for me.

How can I improve my problem solving skills?