Why does everything have to be so difficult???
Both routers have the latest firmware.
The RT-AC88U is reset to factory settings, the AC5300 finds it thru WiFi and tries to setup AiMesh but always fails. I tried setting them up on my iPhone, same issue... Failure...
Added a direct cable between the two routers (AC5300 lan connection, AC88U wan connection).
Success.
Shut both routers down, removed the cable between them. Booted my primary router first (AC5300). When up and running powered on the AC88U and walla! AiMesh is alive over WiFi.
