RouterFix  ›  IspIndependent support guide

How to Fix Double NAT with ISP Gateways

Double NAT often means two local routers both translate addresses; disabling the wrong one can break ISP services.

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Before you change anything

This is a diagnostic entry point. The source supports the general check, not a confirmed root cause for your device.

What to check first

What address range appears on the router WAN side, and is another router upstream?

Record the exact model, hardware revision, firmware and recent change before adjusting settings. If you cannot answer the question, keep the cause open.

Narrow the likely path

Diagnostic branches
ObservationNext check
WAN is in 100.64.0.0/10Ask the ISP about carrier NAT and reachable addressing before opening ports.
WAN is private RFC 1918Identify the upstream router and choose a supported single-routing arrangement.
WAN appears publicCheck router firewall and game-service status; do not expose router administration.
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Decision after the first test

Compare the personal router WAN range with the ISP gateway LAN and identify which box should run DHCP/NAT.

Use a documented next step

Verify before escalating

After each change, repeat the exact failed task. If the result is unchanged, restore the previous setting and use the official support link for your exact hardware revision. Don’t assume a menu or capability from a related model.

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Official sources

Check your exact US model, hardware revision, and firmware on the linked support page before changing settings.

Keep going

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