@DAServices In your case there is no need for the AC5400 unless it is in "Bridge mode" and is functioning as an expensive switch. I might be wrong but AC5400 has a higher spec CPU as a router...
@DAServices Thanks for responding! "Can I use Ethernet backhaul to connect 2 x M9 Plus? The slave M9 Plus is blinking red every 30-60 seconds when connecting both, they are running on AP mode." You...