I’m using the app on Android. I have 5 cameras, setup the first two successfully after adding the MAC address. I had to leave the rest for another time, and on the remaining cams, I can’t get past the QR code read message. I can’t remember how I added the MAC address and can’t find it in any if the troubleshooting places I’ve looked. Other than adding the MAC address I’ve done all the suggested troubleshooting steps. I’d really rather not sit on hold waiting for live help, so would appreciate any help here.
If by adding the MAC address you mean allowing it in your router, then that would be up to you - check instructions online for configuring your router / firewall model, and maybe temporarily disable excessive security features. This is normally NOT necessary when adding a device to a home network. The other big thing that can help is turning off your phone’s mobile data while installing the camera.
My MIL lives in a retirement community and their internet access is a “Community Connection.” You have to go through a portal to connect. I know there’s a place in the app that shows the MAC setting, and since I did it successfully for the other two and couldn’t remember how I did it, I thought it was entered in the app settings. When I go back to her house to try again, I’ll look up the info from provider to see if I can solve the problem that way. The router is in an enclosure in the wall. I opened it, but see no way to unplug it. The first two work, so I know I did it right at least twice 
On my V2s the full MAC address is printed right on the label on the bottom of the camera.
In the app it’s under Device Settings, Device Info, but I don’t know how much of that is viewable before it’s first set up.
Yes, I saw it on the cameras. And yes, it doesn’t seem like it can be entered until it’s added, which is the puzzling part since I set up the other two, but of course I simply can’t remember what I did.