Bandwidth control per device - [is it possible?] need help

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but there is something that I do not know how to do, and that is to make a main router.

I have only done 3 dumb ap but it took like 5 weeks to learn how to do and it was only with a youtube that i install it because I did not understand how not to connect the wan and I did not know how to configure it ...

can you give me a tutorial or better a youtube that shows how to connect a wifi modem / router (wifi disabled) with an openwrt router please

openwrt out of the box is a router between a WAN network and a single LAN network, with WiFi disabled.

but it connects normal from the modem to the wan port of the mainrouter and, from the lan port of the mainrouter to the lan of the ap with dumb ap?? is that correct?

Yes that sounds right