Reviewed by Router Setup Editorial Team Last reviewed:

Double NAT occurs when two devices both route and translate addresses, commonly an ISP gateway followed by a second router.

First checks

  1. Check the WAN address of the downstream router.
  2. Compare it with the LAN range used by the upstream gateway.
  3. Decide which device should provide routing, DHCP and the primary firewall.

How to interpret the result

Ordinary browsing can work through double NAT while inbound services, port forwarding, some VPNs and game consoles experience problems. The usual solutions are bridge or modem mode on the upstream gateway, access-point mode on the downstream device, or deliberate forwarding through both layers.

What this symptom usually does not prove

Do not put both routers on the same LAN subnet while they remain connected through a WAN-to-LAN arrangement.

Escalate with useful evidence

Record which devices are affected, whether Ethernet and Wi‑Fi behave differently, the router or gateway status, and the exact time of the fault. This evidence helps distinguish a local client issue, radio problem, routing policy, upstream service fault or failing hardware.

Before a factory reset

Restart the relevant device first and save any ISP, Wi‑Fi, reservation, port-forwarding or mesh information needed to rebuild the network. A factory reset is a configuration-recovery action, not a universal diagnostic test.

Related troubleshooting

Safety: Do not share router passwords or remote-control codes to diagnose this symptom.