For Enableing UPNP ( Universal Plug and Play) In Arris Router/Modem First we just need to access Router Page of the Router That is also known as Default Gateway.
How to know what is default Gateway of any network
Now open the web browser and type the default gateway IP address In Address bar and hit enter.
Then type the username and passward
(default will be ''Username – admin” , “Password – password”)
Note : -Basically in arris Router/modem they have two types of setting to enable upnp.
1 - Advanced > Device Discovery
2 . IN Wireless MENU
How do I Enable UPnP on My Arris Router?