What is UPNP ?
Universal Plug and Play (UPnP) is a set of networking protocols that permits networked devices, and other mobile devices to seamlessly discover each other's presence on the network and establish functional network services for data sharing, communications, and entertainment.
Port forwarding is to allow internet connection from external source like PC or mobile devices to connect to the device inside the internal network such as IP camera .DVR. NVR after firewall or router. in another word, Port forwarding is directing traffic from the outside world to the appropriate server inside your network.
What is port forwarding
UPnP is intended primarily for residential networks. Many new modern and home use routers already comes with this features.With this function the device like ip camera, DVR, NVRs can ask the router to allow traffic coming from a external source to communicate with it, and router will create a port map rule for this device.
UPNP is designed so that it forwards and unforwards as-needed, preventing that issue. in this case UPNP doesnt always work well, so port forwards are the more reliable option.
for example, Think the internet traffic like package that coming from California and arrived at you FED center. FED distribution center is like you router. FED will forward the package to you according to the address on the label, Router like the center has rules build in which will block or allow package to go thought or reject.
Unlike UPnP, Manual Port Forwarding (Port Mapping) rules remain intact regardless of the unit being use or not. If a device with UPNP is enable please do not create manual port forwarding because they will cost conflict on the router.
UPNP does require any network experience mostly is automatic Port Forwarding require to understand a lot of network things create by router. like IP address .DNS .one small mistake can make everything fall