Ad Space — Top Banner

Double NAT

ASUS Router

Severity: Moderate

Source: OnlyErrorCodes.com — Every error code. One place.

ASUS Router Double NAT — What It Is and How to Fix

What Does This Error Mean?

Double NAT occurs when your ASUS router is connected to a modem-router provided by your ISP, meaning two devices are performing NAT on your traffic. The fix is to put the ISP modem into bridge mode (disabling its NAT and router functions) so only the ASUS router handles NAT. Alternatively, set the ASUS router to use a DMZ on the ISP modem.

Affected Models

  • All ASUS routers connected to an ISP-provided modem-router

Common Causes

  • ISP modem is set to router mode and performing NAT, and the ASUS router behind it is also performing NAT
  • Typical when the ASUS router WAN IP starts with 192.168.x.x or 10.x.x.x

How to Fix It

  1. Detect Double NAT: log in to the ASUS router at 192.168.1.1. Go to WAN > Internet Connection and check the WAN IP address. If it starts with 192.168 or 10., you have Double NAT.

    A real public IP (usually assigned by your ISP) does not start with these private address ranges. If your WAN IP is public, you do not have Double NAT.

  2. Contact your ISP and request that they put your modem into bridge mode. In bridge mode the modem passes the public IP directly to your ASUS router and stops performing NAT.

    Some ISPs call this PPPoE passthrough or modem mode. Not all ISPs support bridge mode — ask specifically whether their supplied equipment can be put into bridge mode.

  3. If bridge mode is not available, log in to the ISP modem admin page and add your ASUS router WAN IP to the DMZ. This forwards all traffic to the ASUS router, effectively making port forwarding work as if there were no Double NAT.

    The ISP modem DMZ is different from the ASUS router DMZ — you need to set the DMZ on the ISP modem.

  4. Alternatively, connect the ASUS router in Access Point mode (disable its DHCP and NAT) and use the ISP modem for routing. This is simpler but you lose the ASUS router features like QoS and AiProtection.

Frequently Asked Questions

Does Double NAT affect internet speed or gaming?

Double NAT does not reduce download or upload speed noticeably. However, it causes problems with port forwarding (ports cannot be opened correctly), NAT type in gaming consoles (shows as Strict or Type 3 instead of Open or Type 1), and some P2P or VoIP applications. For casual browsing and streaming, Double NAT causes no issues.