Double Network Address Translation (NAT) Issues
Having more than one device performing NAT on a private network, however, can cause issues with that network.
This can cause devices that rely on a primary IP address to fail. Issues like no video delivery over stream are common when 2 or more NAT devices exist in the same network.
How to determine Double NAT issue:
One quick way that usually shows if double NAT exists is a traceroute, which allows you to ping a server or device on the internet and see the path it takes between routers and servers. Open a Command Prompt (on a Windows PC that’s connected to the internet, click on the Start menu, type “cmd,” and hit Enter) and type “tracert 8.8.8.8“ to see the traceroute to Google’s DNS server. If you see two private IP addresses listed in the first two hops then you have double NAT. If you see only one private address and the second hop shows a public address, then you’re all good.
How you can fix it
Once you have confirmed the issue is Double NAT, one simple way to resolve the issue is to unplug any additional router and only use your ISP’s gateway.If you’d like to keep your router, see if you can put the ISP’s gateway into bridge or passthrough mode. This will disable the gateway’s NAT, firewall, and DHCP functions and reduce it to a simple internet modem.If your ISP gateway doesn’t offer any bridging functionality, consider putting your router in the DMZ (demilitarized zone) of the gateway. If the gateway has a DMZ, it will basically give the router a direct connection to the internet, bypassing the gateway’s NAT, firewall, and DHCP so that your networked devices get those values directly from your router.
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