I note that this post never got answered (I guess its a known problem that DFRobot do not want to address?), but I know for sure now there is a serious problem with the wake-up custom phrase!

A fellow developer has had the exact same problem as me in that the custom wake-up world is only accurately heard for about 15 minutes after activation - then you are lucky if it works one in six times!

I have now purchased 3 of these units and they all have the same fault?

DFRobot produce some of the most exciting maker devices on the planet! but many have faults like this that are never seem to get addressed which is such a pity.

If this VR unit did not have this fault, then it would be amazing! - but for now, you are going to have to use the wake phrase “hello robot” if you want it to work continuously.

DFRobot team please get back to me with what's happening with this bug/fault - thanks