Main router should have the most powerful processor as it needs to process every network packets going thru the internet "In and Out" from all your connected devices.Can optimise further with this wired setup:
https://1drv.ms/u/s!AmjP4mMSG_m6rUhuFIIHIWwgDLiQ?e=ojItWU
First connect ONT to WAN port of AX58U placed in living room as router.
Next connect LAN port of AX58U to WAN port of AX6000 placed in bedroom using the second LAN point in the living room. At the patch panel connect the living room port to the bedroom port using short ethernet cable for ethernet backhaul. Alternatively connect to your switch if you need ethernet connection to all rooms.
The reason for using AX6000 as node is because bedrooms typically have heavier wifi usage compared to living room. Overall wifi performance will be better.
btw AX58U is a low end router...