I finished my Ph.D as an experimental physicist 20 years ago, and got a post-doc. And I managed to get a job in IT after that. A few comments on your story:
(1) Physics to network technology is not a natural jump. Your resume should be highlighting all the relevant experience you gathered while doing your PhD. I did a lot of heavy coding for data analysis, big data crunching, and unix system administration on cutting edge hardware. My other option besides the Sales Engineer job I ended up taking was translating particle transport code from Fortran to C++. When I was looking for a tech job, that was the experience I emphasized, not the actual physics part. (2) As others have mentioned, you need to be talking to small shops, you're more likely to talk directly to the hiring manager, rather than a HR person. (3) As many have already said, eat some humble pie. You very obviously didn't do your research before deciding to pursue a PhD in Physics. And you haven't been pursuing the obvious route of getting some network certifications. I mean, come on, what evidence are you providing potential employers that your networking knowledge is at all current, or even still exists? And yes, the Ph,D. hurts, the problem is that they think you will want to be paid commensurate with a Ph.D. with your full years of working experience, rather than paid as a network engineer with years of experience up to when you left the field. They are worried you will get bored, consider the work beneath you, and you will either leave or become a problem employee. (5) Take some contracting work. The bar is lower, because if you don't work out they can just end the contract. And that will pad out your resume with the relevant experience.
The only time my Ph.D. was a liability was in getting my first job. You need to establish a job history post-Ph.D. that shows the sort of work you are willing to do for a reasonable amount of pay, for a reasonable length of time. I kept my first technology job for five years. Then, the Ph.D. was never again an issue, it was only an asset. You might need to do contract work for a year or two to establish a similar sort of track record.