Hi @Clem73666 (and future readers), I just wanted to circle back around to this as I could replicate the issue (nas/cifs folder not mounting on boot) with WiFi hardware on another project. I found this workaround, open terminal and then run:
sudo raspi-config
Choose System Options then Network at Boot
The cifs share was reliably mounting after that, including with a Pi Zero that I ended moving the project onto afterward (which boots very slow by comparison to RPI 4, so a good sweat test for this method being resilient).
I guess the key downside is the boot won’t work unless there is a network to connect to. A workaround would be to connect via ethernet if ever you change the WiFi password and forgot to update your RPi beforehand.
