Since the past 2 weeks, every one of my Echo Dot 2 devices (5 of them) revert to full volume after being powered off then on (rebooted.) They stay at full volume until either: 1) I tell Alexa to lower the volume or 2) I push either the volume up or down button once. Doing either of those 2 things would cause the Echo Dot 2 devices to return to the previous volume level.
Prior to 2 weeks ago, the Echo Dot 2 devices would automatically be at their pre-reboot volume levels after a reboot.
A few more things:
There is no longer a reboot tone and "Hello" notification during boot-up.
There is also now a noticeable delay before the Start of Request tone.