Unable to connect Asus RT-AC66U B1 router with centurylink modem router combo C400LG or C3000Z.


New Around Here
Need help connecting Asus RT-AC66U B1 router with centurylink modem router combo C400LG or C3000Z.
I have both centurylink devices C400LG or C3000Z and I tried with each but was unable to establish WAN connectivity.
Below is the setup;
DSL cable --> Centurylink device (WAN/LAN port) --> (WAN port) Asus Router
I tried few steps but I was unable to make it work;
On centurylink device I did following;
  • Disable 2.4GHz & 5GHz Wireless Radio > Disable
  • changed ISP Protocol > Transparent Bridging
  • “Transport Mode” dropdown as “Tagged-201”.
On Asus router I did following
  • Changed the Asus router to router mode
  • WAN connection type changed to PPOE
  • Upadted PPOE user id and password
  • Changed LAN ip address so it is different from centurylink device.
I don't know what I am doing wrong here.

I also followed https://www.metageek.com/training/resources/use-router-with-dsl.html


Part of the Furniture
Sorry, I don't have any experience with your kind of setup. There are some posts from other members with the same configuration as you and it "just works". So I'm wondering whether, as your ISP's website says, it's simply not available in your area. Have you tried contacting your ISP and asking them what setting you should be using for your area?


Very Senior Member
@joang16 - If CL confirms your traffic needs to be tagged, select Transport Mode, option 1 (Tagged-201), but you'll have to mark your own WAN traffic on egress from the router with VLAN 201 (per this Reddit post using an OPNsense box). I'm not sure if AsusWRT (or Merlin) is capable of that; you may need to flash a firmware that can, such as FreshTomato, or just put in a fully VLAN-capable router such as a Ubiquiti EdgeRouter-X or similar in place of the Asus. Also, make sure VPI/VCI is correctly specified 0/32 for CenturyLink on the C3000Z.


New Around Here
Thanks Colin Taylor and Trip, I will try contacting my ISP first next week and perform above suggeted setting. Will update once done.
Last edited:
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