Router positioned beside another router without using double NAT
Router positioned beside another router without using double NAT
Hello everyone, my query concerns configuring a router in front of another router. Reason: The ISP router is essentially a black box and I can't modify it. This setup combines two modems—one providing an 8Mbit wired connection and the other a 22Mbit LTE wireless link. Details: I cannot disable DHCP or set a preferred DNS. At least I can create a DMZ and assign static IPs. The idea is to place another router after the black box, manage LAN and WAN, turn off NAT on the second router, enable DHCP there, and use the preferred DNS for my subnet. Would this approach work? I’d prefer to avoid double NAT complications. Please let me know if you need more details or recommendations. Thanks!
I faced a problem once where I couldn't establish any link with the other router/modem, regardless of port, cable, or software adjustments. It seems this might not be possible with my devices. This is just a personal experience—no general solutions provided. Hope you find success eventually.
It seems DHCP typically needs NAT support to function correctly. The setup might rely on the second router being configured as a DMZ with proper gateway settings. If that's not possible, double-NAT can become complicated because features like UPnP or NAT-PMP won't work without proper configuration. You'd need to manage port forwards between both routers, which isn't ideal but may be necessary given your setup constraints. The main challenge is balancing performance with flexibility, especially if the primary router isn't handling the traffic efficiently.
Sure, I understand. You're planning to proceed in that direction. Your main goals include monitoring, configuring preferred DNS settings for all clients, and similar tasks.
If you can't attach routes at the beginning of the router, you'll have to double the network.
You are going to need to have some type of NAT on your first router (Black Box) as you have no other way of routing the internet to your next router Unless the black box supports 1:1 or static Nat then the only way I can see this working is by having NAT. 1:1 or static NAT would be ideal but you will likely need to use standard overload/masquerading NAT to break your public address into a routeable private address that you can pass though to your second router. This shouldn't cause too much trouble other then port forwarding which you would need to do on both routers unless you choose to route from your second router directly to your black box router using either a routing protocol or a static route.
I help with ISP matters and know that rental gateways can switch to bridge mode when needed, letting your own router function smoothly. Alternatively, think about purchasing a modem instead.
Avoid using two modems directly into the main router since this requires routing for load balancing or failover when the primary link fails. Alternatively, consider isolating their traffic with VLANs—though this isn’t likely supported on standard ISP routers. It might work if the main router operates in bridge mode and connects the LTE modem to a secondary device, but it seems both connections remain linked to that central unit.