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Hi Carlos, Thank you. I don't know if Vincent resolved the issue but are you able to try it from a different device and also try changing the channel in the hostapd.conf file just in case of interference?

The other option is when the hotspot is up, stop hostapd and run it manual and see what feedback it gives.
enter: sudo systemctl stop hostapd
then: sudo hostapd /etc/hostapd/hostapd.conf
then try to connect your device again and see what feedback you get, add -d or -dd to see more detail, actually quite a lot :) sudo hostapd -d /etc/hostapd/hostapd.conf

Also check dnsmasq is still running ok with sudo systemctl status dnsmasq it should say active in green and no errors in the lower text.

just to confirm your changes
/etc/dnsmasq.conf will have

and the autohotspotN script will be
ip link set dev "$wifidev" down
ip a add brd + dev "$wifidev"

Let me know how you get on either way. If still an issue I will look into it further.