Thanks for that, however I have already followed those instructions.

I get the same error everytime that there is already a WAN or IPTV setup without a VLAN ID so it can't make a new one.

I am having the exact same problem with the same error code for my MR400 V2 router. When setting up the WAN connection, it asks for a VLAN id, and whatever I put in it, it says 'WAN connected', but there is still no internet access. The 3G/4G mode works fine.
My LAN IP is 192.168.0.1 and provided WAN IP in 192.168.1.110.
The internet works fine when connected directly to my PC.

@WhatToDo 

Have you solved the problem?

@WhatToDo 

Hi,

I had similar problem and resolved it in following way:

In Advanced mode - > Network - Internet :
set Dynamic IP and expand Advanced, then check box with - get IP using DHCP Unicast type.

NOTE: IPTV is disabled and Archer has different LAN then fiber router.

Hope it will help for you too.

cheers,

M

@WhatToDo I am fighting to get my MR600 to work in Wireless Router Mode too.
I have followed the instructions here:
https://www.tp-link.com/dk/support/faq/2719/

I must be missing something, as I do not get any WAN internet at all.
Nothing shows up under my Internet Connections a part from a 3G/4G connection that is working fine.
 

Am I missing to tick something off somewhere ?

Must I add a WAN connections to the list manually ?

@peterholm The only thing that worked for me was letting 'Quick Setup' find the WAN connection. I got the impression the error checks on doing it manually must be wrong.

@WhatToDo 

I run into the exact same issue with Archer MR400 in my case NOT letting me create a new WAN interface with VLAN 0.

Apparently, the SIM-based WAN interface which is created by default takes over VLAN with ID 0 and this is not configurable. 

In my case the router that I was trying to connect as a backup would also not allow me to configure a different VLAN to the LAN port that I had connected my MR400, which is common. 

The ONLY thing that worked was to do a factory reset to MR400, then proceed with adding the Backup WAN interface BEFORE setting up the 3G/4G WAN connection. 

Now, in my case, this is acceptable because at the moment I do not use the SIM slot.
However, I am not sure if this will still work after setting up the 3g/4g WAN connection.

Hope this helps. It gave me a BIG headache...