For a microphone, you need to read the specifications for that model of camera. I tried guessing one a few years ago and never got it right. Speakers shoud be easier as I think a line output should be pretty standard. Being able to return items would take the risk out of either purchase. Jennov ptz ...

Well I'm not Harry Potter, so no magic. We have seen this before and it could be a missed setting or a corrupted setting. The good news is it rules out a lot of things even if it doesn't work

That seems to be normal with Reolink. I had the same with their doorbell camera. Well done finding it

Could Powerline ethernet be another option with the existing camera ? I'm using the G.hn protocol type here for two Dahua PTZ's that I couldn't get an ethernet cable to.

Can you try cloning one of the identical working cameras and then changing the IP, username and password to see if that helps ?

It looks like a bargain, but the OP didn't respond

If that is recent, it will be for BI5. Please check.

And after that, does this camera have audio ? If not, ensure Audio is OFF in the BI5 camera settings, else the BI5 watchdog will keep stopping the camera.

Hi, anything in the Log ?

I haven't bought a camera for a few years either so I guess just buy from somewhere you can easily return them to if no good and bench test the first camera. Does the NDAA compliance issue affect you ?