Are you using M7350? This MiFi router don't support port forwarding function. So we may not open port on it.

Can you connect to the Internet? Please check your network IP address. Make sure you choose Obtain IP address automatically. Then enter the default gateway in web browser and log in the Web UI.

M7350 don't have port forwarding option. So we can't open ports on it.

The router only reads the data from the modem. So we can't force 3G on the router. You can connect the modem to the PC first and set it to 3G only. Then connect to the 3G router and check if it work...

You need to set port forwarding for DVR on your 3020 router. Open port 5000 for IP 192.168.3.10. Besides,make sure MR3020 got an Public IP address. Hope this can help you.

I asked tp-link and they said they will release a firmware to solve the problem later. Maybe we can try the new firmware when it released.