One network, two routers doing the same job twice. Double NAT hides quietly behind a hundred strange problems - here is how to spot it and remove it cleanly.
NAT is the router feature that lets many devices share one public internet address. Once is correct. When the ISP's router does NAT and your own router behind it does NAT again, you have double NAT. Ordinary browsing survives it, which is why it goes unnoticed - but online games show Strict NAT, port forwards refuse to work, some VPNs and video calls glitch, and devices on one router cannot see devices on the other. The fix is to make only one device the router. There are two clean ways.
Two private 192.168 addresses in the first two hops means two routers are NAT-ing. One hop should be private, the next should already be the ISP.
tracert 8.8.8.8192.168.1.2 instead of a public one, something upstream is already routing - that is double NATBridge mode turns the ISP router into a plain modem: it stops routing and passes the public connection straight to your router, which then does everything.
Honest note: on fibre ONTs the ISP may keep voice or TV services tied to their box; ask the ISP before bridging if you use their landline or IPTV.
If the ISP router cannot bridge, reverse the roles: let the ISP router stay the only router, and demote yours to a simple access point that only provides WiFi.
Do not try to fix double NAT with port forwarding on both routers for every service - it half-works, breaks on the next change, and still leaves game NAT strict. And the DMZ option on the ISP router pointing at your router is an acceptable shortcut, but understand it honestly: it forwards everything to your router, so your router's firewall becomes the only wall - fine if your router is good and updated, risky if it is not.
See every menu and setting live on screen - WAN, LAN, WiFi and security, in the exact order of this guide.
▶️ Watch Full VideoFor browsing, streaming and office work it is mostly harmless, which is why millions of homes run it unknowingly. It becomes a real problem for hosting anything, port forwarding, some games and consoles, site-to-site VPNs, and when devices on the two routers need to reach each other, like a printer or NAS.
Bridge mode, if your ISP allows it - your own (usually better) router runs the network. Access point mode is the practical choice when the ISP box is locked, or when the ISP router is actually good and you only bought yours for better WiFi. Either removes the double NAT; running both routers as routers is the only wrong answer.
In AP mode the router takes an address from the main router's range. Find it in the main router's connected-devices list, or use the fixed LAN address you set in manual AP setup. This is normal - the device is now a citizen of the network, not its gatekeeper.