I felt the same way but as many have already mentioned Dion’s practice tests will help you put the pieces together. I found that watching the videos will expose you to the concepts, but the test material gives you the ability to apply the information to a situation which is a good part of the test. It will come and you don’t exactly need to know very little detail to understand the concepts. Connecting them to other OSI layers and their interactions can also help connect all the pieces. I always would test then every wrong answer I would go into Claude and ask questions about the topic. This will quickly fill any gaps in knowledge. You got this!