@Fowlet Please check this link out, if not already done.

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

Abhilash.Jena wrote

@Fowlet Please check this link out, if not already done.

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

@Abhilash.Jena this is the reverse of what I need. I need 4G to be the primary connection, and fall back to ADSL when it fails. 

@Fowlet did you ever get this right? I'm in a similar position - when it works the 4g connection is preferable but I'd like to switch over to the more reliable DSL connection (available over LAN)

@ahoydave unfortunately not. I'm 90% sure it's not possible. I even looked into flashing the router with custom firmware, but nothing was available about 6 months ago - maybe that has changed? Unlikely.

I know it is possible if you use something like ROOter (Openwrt based) but MR600 isn't on their supported list unfortunately

https://www.ofmodemsandmen.com/routers.html

It's a pity since they've got the logic in there to go the other way round :-/

Hi Guys,

I achieve this using a slightly different method using a TP-Link router/load-balancer.  Check out the link below:

https://community.tp-link.com/en/home/stories/detail/1370

CheerZ