The narrative you post is extremely hard to follow and makes little sense. Let's try to decipher.
You lost your job when then dot com bubble burst and went back to school. You finished a PhD in Physics. You then found out your were sold a bill of goods about jobs of people with PhDs in Physics and there is some sort of glut.
Then you have been doing some sort of project management for DoD and NASA. Now is where things get really weird.
" I desperately want back into network equipment product management, but my networking tech skills aren't up to date."
Pulling that apart, you are talking about a job more on the business side than the technology side of the business. Technical skills are important in product management, but so is a head for business. That could be one reason that people don't "get' you -- they see that you went back to school and spent time and money on getting a PhD in Physics. You didn't go back to school to get an advanced degree in CS, EE, or a MBA. You went back for Physics and now you are trying to get into product marketing. But things get a little weirder.
"I find networking technology absolutely trivial"
I really, sincerely hope this is a typo. Finding something "trival" has considerable negative connotations to it, and if you say that to a hiring manager, they are going to think you are going to be just biding your time with their "trivial" nonsense product and looking to move onto something more interesting the moment it shows up. It would be better to say that you enjoy certain challenges or explain what you find interesting rather than saying something is "trivial".
And then finally,
"I'm more than willing to start over in network admin"
I don't see that you need to move to this, you need to concentrate and present the skills you have and exercise in program/project management and previous skills to get into some sort of networking gig. But you do need to address some rather good questions a hiring manager would have, specifically:
- Why did you get a doctorate in Physics when you were interested in product management?
- What excites you about networking and product management?
I also highly recommend that all job seekers thoroughly read and use "What Color is Your Parachute?". If nothing else, it will walk you through making a coherent case for yourself of why you want to pursue a given career, and that coherent presentation is going to make hiring managers stop running and start listening more. Right now if I was hiring a job that was responsible for setting the business direction of a networking product, I'd be worried about hiring you because your record shows you actively running from the business development aspects of your career.
Your Physics degree is certainly not worthless and should not be hidden. You can most likely take on complicated problems, decompose them at a high level, aren't afraid of the unknown, etc. Also the fact that you finished your PhD means that you can stick with something, too.