Router RT-AC750GF

Hello
I am installing an Asus RT-AC750GF router using the OpenWrt installation protocol (https://openwrt.org/toh/asus/rt-ac51u) and the installation stage is blocked at stage 8 of the website, the restoration tool is blocked and refuses to transmit it to the router with this error message (‘no wireless device found in recovery mode’).
thank you in advance for your help

Only the AC750L is supported by openwrt, are those two the same ?

wiki-devi claims it is equivalent to RT51U

The "no wireless device" message is when you have other network interfaces enabled on your computer while asus tool is running

Thanks for your help, but I've tried to follow your advice but nothing works.

I didn't provide any advice, only a counter question ...