Let me elaborate a bit more.
Want total control upstairs,no wifi.
Total control downstairs,wifi6
RT up top,AX down but into which lan socket on the AX do I put the cable from the RT and what mode to use?
Want the AX to be its own boss,pass out IP's etc and use wifi6
Need to be able to enter it's UI
RT upstairs needs to be the king,especially for gaming,cat7 to my gaming pc
then it just needs to pass/share the internet downstairs through a lan cable
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Achieved
Advanced/LAN option in RT
Set IP/dns as desired
DHCP Server tab
Down the bottom,Manually assign IP's
Gave the AX next IP,my pc next after that
LAN cable from RT went into WAN port,pc into gaming port.
Router mode is chosen in the AX,Automatic IP.
Advanced/LAN,different IP network as desired.
Wifi configured