How to actually learn the fretboard

Can someone explain the fretboard so it's as easy to understand as, say, the piano?

I've watch a whole ton of videos but it seems like everyone has methods but no one covers it enough for me to get a clear idea.

So far I've learned: - memorizing the fretmarked notes - using the circle of fifths - next string on fifth fret

But I'm still really confused where, say, the octaves begins and ends, where the same notes with the same frequency are, or the next frequency note/octave begins, if that makes sense

It's all realt confusing and unclear to me. I feel like I know bits but not the whole fretboard. Can anyone help me out?