1. Do you have a public IP on the SIM that is inserted in your router?
2. VIA should be the IP of your router, so for example: 192.168.1.1 and any port you like, as it will be used to connect from external network and has nothing to do with the destination port.
3. Also, make sure you enabled remote access in System > Administration > Access Control
In the end, you should be able to reach your camera from external network with address: yourPublicIP:8800