Bulb keeps dropping from Wifi

I have a Yeelight bulb that seems to keep dropping from being able to be accessed.

It’s connected fine one minute then seemingly randomly it stops responding to commands (via Alexa) and checking the app it’s shown as offline. Turning it off an on again restores the connection.

Why do the bulbs not try and re-initiate connection when it is dropped? And if they do, why is it failing?