Volumio doesnt start on first "cold boot"

I have volumio on an RPI 2 with wifi dongle and a IQAudio digiamp+.
Every day when I plug in the power, it doesnt boot correctly… where I am not able to connect via SSH, and the startup sound does not play. The wifi dongle blinks.

If I cut the power and replug it a few seconds later, it starts fine. It doesn’t matter if I turned the RPI off nicely via the web interface or I just unplugged it.
Anyone have any ideas of how to debug? There seems to be very little relevant logging in /var/log.