Not much information here for us to help you. I've had an 88U as a node in an AiMesh system, and it's working great. I'm using ethernet backhaul mode back (so not even Wi-Fi as a backup) to the main router and am using the .386_41994 firmware that's on asus.com. I can only offer two guesses based on past problems with my 88U, but no idea if these apply to your situation. WPS needs to be enabled on the main router for the initial AiMesh setup, but once the initial connection is made it can be disabled. The various .386 firmware builds have not been consistent if they automatically enable WPS or not when placed in AiMesh mode, some do, some don't. I don't remember if the .386_41994 does or not. Also, I did have some bizarre issues with the 88U freezing in one form or another with earlier .386 builds, but not the current one. It seemed to be worse if ther were devices connected to LAN ports 5-8 (there's a number of bizarre issues with the last 4 LAN ports on that router, just search those threads), you might make sure those ports are disconnected while configuring the AiMesh.