The UID status on the IP camera’s user interface should be
“Connected” otherwise, we won’t be able to view the
camera through EnViewer.

Possible reasons why UID would be “Disconnected”:

• IP camera is not connected to the router and the internet. Verify
  connections.
• IP camera is behind 2 NAT (Router behind router). Make sure the IP
  camera is behind the first router. Better if there is just one NAT.
• The router does not support UPNP Forwarding. Verify it from
  manufacturer. 
• The router supports UPNP Forwarding but it is not enabled