Could be multiple things. Based on some of the things you mentioned a few things come to mind. I could be wrong, but with all of the years of experience and military backgroung(thanks for your sevice), I'd guess you're no younger than 40, but likely somewhat older. While it isn't cool, ageism does exists. You mentioned all of the certs as well. You may be submitting resumes to companies that assume they can't afford you for the role they want to fill. On the other side of that, you mentioned getting back into engineering. Current relating experience might be an issue, if you've been away dealing with IT and plants for a long period of time. Lastly, it could simply be something as your resume. I'd recommend getting with 1 of those career folks, I believe most departments of labor have classes/workshops for resume building and things of that nature. Find someone who can help you go over your resume and make any adjustments for the way things are today. Outside of that, I'd also suggest maybe looking into getting that resume into the hands of recruiters or job boards. I don't know if I can post them here and I'm sure you already know a few, but the dept of labor should have a good list of them. You're not far from a lot metropolitan areas and remote work is probably an option. A lot of companies have become a little more open to that since C19 hit the scene.
If all of that fails, go ahead and start the business you mentioned in a different post