I have done some testing of WyzeCam plus/minus internet.
I booted the WyzeCam with full internet access present, and the camera initialized normally. RTSP worked. I then killed internet access with the firewall. The WyzeCam continued to work - both RTSP and through the Wyze app. Note that I only “killed the internet” for NEW connections, existing connections were allowed to continue, which explains why the Wyze app continues to work after the kill.
FWIW, for you technical people, here is what I did in the firewall to “kill the internet” (note that br2 is the bridge/vlan that I have the WyzeCam isolated on):
iptables -N restricted_access
iptables -F restricted_access
iptables -A restricted_access -p tcp -j REJECT --reject-with tcp-reset
iptables -A restricted_access -j REJECT --reject-with icmp-host-prohibited
iptables -I FORWARD -i br2 -m state --state NEW -j restricted_access
I will go back and run my “kill the internet” test again, but this second time I will kill it totally (wiping out existing connections as well as new ones).
With the internet firewall as above (internet blocked for NEW connections) I unplugged then replugged the WyzeCam forcing a reboot. The WyzeCam would NOT fully initialize with no internet access. During an normal initialization, the WyzeCam LED goes SolidYellow -> FlashingYellow -> FlashingBlueAndYellow -> FlashingBlue -> SolidBlue. Without internet access, it hung at FlashingBlue, therefore not fully initialized. The camera was non-functional in this state.
So my conclusion is: The WyzeCam REQUIRES internet connectivity to reboot. Without internet availability during boot, the WyzeCam is about as useful as a rock.
However, if the WyzeCam is already booted and functional when internet access disappears, it will apparently continue to work as a local RTSP stream.
Bottom line: You MAY be able to sneak by and remain functional (local RTSP feed) if internet access disappears and then comes back. But if you also lose power, you are dead in the water if the WyzeCam tries to reinitialize without internet. It is also important to note that when the WyzeCam hangs when it tries to boot without internet access, simply restoring internet access does NOT get you past the hang. The camera appeared to hang indefinitely, remaining hung even after I restored internet acess. After internet is restored, you MUST then subsequently powerdown/powerup your WyzeCam to force it to try initializing again.
This is not ideal. I hope that the developers will at least rework the firmware so that the WyzeCam will automatically attempt to retry initialization if its first attempt fails. The way it is now, it appears that a power failure will hang your WyzeCam. Because a power failure would kill your router too, and upon power restore, the WyzeCam probably reboots faster than your router reboots, so the WyzeCam would see no internet available as it reboots from a power failure.
Final note: I ran my test once, so that is only one data point. It is possible that running the test multiple times might produce different results. However, I stopped after one test because that one test proved to me that at least sometimes, WyzeCam initialization will fail with no internet available. Even if it only fails one time out of ten, that’s still a chance that you need to be aware of if you have remote WyzeCams where you cannot easily go over and unplug the thing to force a reboot.