tone degrades fast - beginner question

All - As I’m learning some beginner songs that get a bit longer I notice as I move across the octave the tone diminishes quickly. To the point where I can’t make a clean note at all. I don’t believe it’s related to the covering of the holes as I verify all is good there. Is this possibly “clogging”? I hope not because I’m using a Sweetone with a plastic mouthpiece. I thought they were to be fairly good at reducing clogging issue?

Is this some type of technical playing issue that is related to my skill? For example i start a song with a low D and it’s perfect. Can play it several times with no issues. I’ll play up the octave and then back down and can’t play a good D whatsoever. Very annoying.

Thanks

AB

Most beginner issues are solved by time and practice.
Stick with it and the skill will come, even if slowly.

Place a finger over the window (so there’s no sound) and blow hard.

That will probably clear it.

I spent a good part of the day working on this and it seems that if I curl my lower lip back. Nothing crazy just a little that it stops the issue from occurring. I’m thinking it is some type of clogging occurring when I don’t curl my lower lip back.

You can clear a clog quickly even in the middle of a tune by sucking in sharply. No need to take a hand off the finger holes.
A very mild solution of dishwashing liquid like Dawn (2-3 drops in an ounce of so of water) dribbled into the windway will help prevent clogging. Shake out the excess.