I lost connection to all v3 cameras. I unplugged them, reset the modem. They won’t reconnect.
Go to the Account > App Settings and Clear Cache from there.
If you have Android, shut the app down and long press the app icon. Go to App Info, the do a Force Stop. Click on Storage and Cache and Clear Cache. Do Not Cleat Storage.
Restart your phone or tablet.
See if this helps you.
In the past I had a similar issue and after doing this, it came back.
Note: I also Formatted my SD Card as well, but don’t really think this did helped.