I can only connect to my DVR on my Wi-Fi (not 3G/4G)
If you are experiencing issue connecting to your DVR remotely when not on your Wi-Fi this may be your modem blocking your internet ports.
These ports allow your DVR to send out information to the application so you can view your cameras live away from home.
Due to this being through your modem itself, if this is the cause you will need to contact your internet provider and ask them to unblock the mobile ports.
This is a fairly common issue with modems connected to a security system.
To our knowledge, the ports mentioned are 80, 5000 and 5001.