To check if you have double NAT, you can use the following steps: 1. Open a command prompt on your computer. 2. Type "tracert" followed by the IP address of a website or server that you can access from your network. For example, you could type "tracert www.google.com". 3. Look at the first two hops in the tracert results. If both hops are private IP addresses, then you have double NAT.