I'll give it a go. Having a quick read of both links, they look like they are for setting up the ASUS as primary devices and not as an AP behind another router. My initial attempt is to try and keep the Archer as the primary to keep the VOIP service. Otherwise, I'll attempt to change the vlan id to 2 as specified in the first link.
Maybe in bridging mode, VoIP doesn't work. I haven't fully grasp what is meant by bridging. Let the community know if you are successful with connecting both the routers. From having experience with a repeater, WPS seems like the easiest way to set up the connections.
Actually, now I'm not sure if WPS will work for you. Repeater WPS is easy but never tried for router to router. From reading this: https://forums.whirlpool.net.au/archive/2517183 , try to set your WAN connection static IP to dynamic IP.
If you are trying to set up ANY router as a second AP, the only way I've found successfull is to disable DHCP on the second router, set it's network IP to a fixed address and then connect to the main router via one of the LAN connections. Don't try the WAY/DSL connections it won't work. It won't be a router with firewall etc, but your're only trying to add aweifi acces right?
On some NetGear routers there are confiduration options for the second to be bridged to the mnain router.