play 1 and 5 disconnected

have a play 1 and play 5 connected by wifi for years. recently sonos app reports no speakers are connected.  leaving the play 1 untouched, i connected the 5 via ethernet and it worked as did the 1 still on wifi.  by disconnecting the ethernet cable from the 5, the wifi connection on the 1 was lost.  how do we get both of these back on wifi?,