I have 4 volumio systems all running v3.912 on rPi3 with hifiberry amp2. This problem has been happening for several versions and volumio microsd cards will have been reflashed several times in the period in which it has been happening.
On a couple of the systems volumio doesn’t remember the volume setting after a reboot - it resets the volume to 100%. This is particularly annoying if it does an auto reboot in the middle of the night and Startup Sound is on!
Yes sorry I was about to create log URLs but then noticed there is a Version 4 released so started trying to install that. That failed to load so for now I factory reset and reflashed the raspberries with v3, and for the moment can’t reproduce the “full volume” problem.
I will create new post detailing the problem I’m having installing V4