@lorengd TBH I've not used the multi WAN functionality myself so dont how it works in detail. Hopefully someone whos used it in anger, or a staffer will have more information

@lorengd Check your Load balancing and link backup configuration. Note that you need Load balancing enabled to get link backup functionality https://www.tp-link.com/uk/support/faq/2133/

@lorengd When the connection is down, the SR203 intercepts DNS requests and returns the landling page to all requests. This means that the DNS request is seen as successful and so the ER605 beleives...

@Sam_CS Another thought , have you tried cloning the MAC from the ISP supplied router ?

@Sam_CS From what I can see, you are getting a successful PPPoE connection ( with the VLAN ID set ). Try disabling the online detection ( set to always online ), does that give an internet connection...

@Sam_CS I'm not sure exactly how the 'online detection' works on the ER605 but I suspect it pings the ISP gateway and/or sends a DNS lookup to the ISP DNS servers. Its distinctly possible that your...