Fix Double NAT Issues

1. 1

   Confirm double NAT

   Run a traceroute (tracert 8.8.8.8 on Windows). If you see two private IP addresses (e.g. 192.168.x.x then 10.x.x.x) before a public IP, you have double NAT.

2. 2

   Identify which device is the outer router

   This is usually the modem/router supplied by your ISP.

3. 3

   Option 1 — Enable bridge / pass-through mode

   Log in to the ISP modem and enable Bridge Mode or IP Pass-Through. This turns it into a pure modem and lets your router handle NAT.

4. 4

   Option 2 — DMZ the inner router

   In the ISP modem's admin page, add your router's WAN IP to the DMZ. This passes all traffic to your router.

5. 5

   Option 3 — Use only one router

   Connect devices directly to the ISP modem if it has enough ports, removing the second router entirely.

6. 6

   Confirm the fix

   Run traceroute again — you should now see only one private IP hop before the public address.

Frequently Asked Questions