What’s a double-NAT and how can it cause trouble?

Your internet service provider (ISP) usually assigns your home internet connection a single public and globally unique IP address, known as WAN (Wide Area network) IP. Most households have multiple devices connected to its home network, with each device requiring their own IP address.

Your router assigns a local IP address, also referred to as Local Area Network (LAN) IP, to each device in your home network. Local IPs follow a special format such as 10.x.x.x, 172.16.x.x, 192.168.x.x.

Your router then transfers data that comes in or goes out from the public IP address to the device in your home network. This process of transferring data from the public IP address to the specific device local IP address is called Network Address Translation (NAT).

A double NAT happens if you have two routers connected in cascade, or if you have a router connected to your ISP modem which also acts as router itself. All this means is that data is going through a NAT process twice. The picture below illustrates this concept:

If WEPN Pod is behind a double-NAT, it won’t be able to perform port forwarding operation and have the internet traffic directly routed to itself. 

WEPN compatibility test would attempt to check if the router you are connected to, has a public IP address (WAN IP) or private IP (LAN) address. If the router itself has a private IP address, it means that it was assigned that local IP address by another router on the network and not by the ISP. In rare cases, ISPs do not assign routers a public IP address and use Carrier Grade NAT or CNAT. This can also create an issue for WEPN Pods. For more information regarding CNAT check out this article: