@WhatToDo 

Hello, below is the instruction to setup 3/4G backup on the MR600. You need connect the fiber router to the LAN4/WAN port of Archer MR600 by wired cable and log into the web UI to change the operation mode to wireless router mode first.

https://www.tp-link.com/support/faq/2719/ 

Please ensure that the firmware is up to date. And if it is still the same, please show us a screenshot of the error message you saw. 

Good day. 

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.