I have a TP-Link 740N v3 router with WAN port and LAN port 1 burned.

I was able to flash DD-WRT and to apparently configure WAN port to LAN port 4 (or 1, I don't actually know how are they numbered by kernel).

Laptop on Wi-fi receives a correct address, from 192.168.1.* network.

But PC, on a wire, receives an IP address from 37.* (for example) network. After that, routing from Internet to Wi-fi 192.168.1.* network stops. When PC is off, Internet appears on 192.168.1.* again. Apparently, PC grabs an external IP and "all the Internel" from WAN.

Is there anything except vlan1ports/vlan0ports I should configure?

Some diagnostics, ipconfig and so: https://gist.github.com/92899e26d2e35897714c

What else do I need to change to get port 4 to be WAN and wired ports 2-3 to be LAN (onto 192.168.1.* network)?


Apparently I need to add another VLAN for local Ethernet ports, other then the "new WAN" (port #4). That's because PC gets an IP over Ethernet directly from WAN, and I need PC to be on LAN (192.*) network.

But my router doesn't have a VLAN admin GUI, though it's of the same version - v24 preSP2.

I followed all the instructions to separate Ethernet ports into different VLANs, and still no luck, PC still grabs an IP from my ISP as if the router was a simple switch.

  • See this link for how to understand port numbers. The entire article has step-by-step procedure of replacing the uplink port. Sep 25, 2012 at 12:24
  • I did follow it, as you can see from nvram show output. Something still went wrong. Do you know what it was? Sep 25, 2012 at 13:22

1 Answer 1


Sounds like you haven't configured the LAN ports correctly yet. The ports are still acting like a hub and not like a firewall; hence the PC grabbing the external IP. As far as I know the areas to look into are VLAN(which you're already doing) and global router settings(like if it's a bridge, gateway or router).

Have you tried again with the latest firmware?

  • I cannot try the latest firmware - I don't have that router any longer. I believe you're correct about the gateway/router setting. Aug 4, 2013 at 13:17

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