Thanks for all the responses! Sorry I didn't respond sooner, I had some stuff come up yesterday. And sorry I wasn't specific about the switch, it's a TP-Link TL-SF1008P Rev 4 (8 ports), it isn't labeled as having a dedicated uplink port and I moved some things around and they worked in all the ports, so I don't think it's an uplink port issue. The specs for the switch make no mention of a dedicated uplink port, just says the ports are auto negotiating. One other bit of info is that I just upgraded to fiber internet so have a new router, which is part of why I'm moving things around. I've had my cameras (4 POE, 1 non-POE) and
Blue Iris setup with minimal issues for many years and have had those cameras working fine since getting the new router as well (about 3 weeks). Then a few days ago I got a 6th camera (making it the 5th POE camera) which started the latest adventure.
In a nutshell, I think I just need to get a new switch sooner than later. Something I've wondered about before is if I'm over saturating it, it's only a 10/100 switch and has 5 cameras on it (3 @ 3.7mp, 1 @ 2.1mp, and 1 @ 1mp), plus my Blue Iris computer (HP Prodesk 600 G1), 3D printer, the router, and a Pi. The one issue I've had over the years with this setup is individual cameras cutting out from time to time, though it didn't happen too often and usually didn't last long, but that's what got me wondering if the switch might be at it's throughput limits (and this was before my most recent issue of adding a 6th camera to it). In case you're wondering why the math doesn't work, I have a 5 port switch on the other end of my house that is plugged into the 8 port switch, and the 3D printer, Pi, and a non-POE camera are plugged into the 5 port switch.
Getting back to the present, I've tried plugging the 5th POE camera into a few different non-POE ports and at one point the camera started working but it didn't last and a couple of my other cameras started cutting in and out. I tested using some store bought short cables and two DIY long cables and even put new ends on one of them (which I then confirmed working using a cable tester) and the camera still won't consistently send data. I also tested that long cable by connecting the HP computer to the switch and it worked, so I'm sure the cable isn't the issue.
So I guess the question now is could it be that the switch just can't keep up with the amount of data and it's turning off ports?