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Author Topic: Two routers, one network... double NAT  (Read 931 times)


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Two routers, one network... double NAT
« on: August 20, 2018, 11:26:14 AM »


I'm trying to figure out what's the best network config to have my WiFi router obtain its internet connection via my Zyxel modem/router. Originally I had the Zyxel in bridge mode, however I have DSL connection reliability issues (REIN), and have connected a failover 3G USB dongle to the Zyxel to compensate. Since that doesn't work in bridge mode (xDSL only) as far as I can fathom, I need to route internet traffic via the Zyxel as the gateway to the WiFi router, while trying to avoid routing conflicts and complexity like double NAT.

There seems to be a few options to mitigate (though not eliminate) double-NAT issues, bearing in mind I'd prefer the WiFi router to handle DHCP

- Put the WiFi router in a DMZ on the Zyxel (current setting)
- DHCP relay from Zyxel router to WiFi router
- Put WiFi router in bridge mode (but lose most network management functionality - not desirable)
- Turn off NAT on the Zyxel router without nobbling the Internet connection (not possible??)


What's the advisable and most network-efficient set up to have in this scenario?



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Re: Two routers, one network... double NAT
« Reply #1 on: August 22, 2018, 04:53:49 PM »

Double NAT is not normally a problem, your 3G probably doesn't have a real Internet address for example so even using that directly would probably mean NAT from your internal addresses onto the 3G external address, then NAT by the carrier.

However, is there any reason you can't use your WiFi router just as an access point?  Give it an address on the same subnet as the Zyxel, and disable DHCP, connect a LAN port on the router to a LAN port on the Zyxel.  The WiFi router will then just be acting as a LAN switch and wireless AP.