shutdown Volumio when home WLAN is down

this feature is suggested because of be aware for electronics radiation and sustainable (less) power consumption.

i like to see a feature to enable when my home wlan is going down.
this function should start a shutdown procedure after some minutes of no wlan connection (because sometimes router is only restaring because of updates)

Background: my router disable wlan in the night for no electronics radiation.

an additional function that only turns off the wifi is also desirable. here is e.g. local music continued to be played until e.g. the sleep function starts.