Unfortunately that’s not much detailed information. Maybe someone here can help, if you share some information about your Sonos system, your network setup and controller device. 
The other option would be to contact Sonos support team directly. 

Turns out a reboot worked. But it’s an issue that comes up too frequently 

This is not a problem for the Community regulars. We need more information about your system or you should work with SONOS support.

Sometimes, setting ip addresses for Sonos devices prevents the need for frequent reboots. But as ​@buzz says, give us more information to avoid us guessing. 

Useful Information would be:

• do you have wifi repeaters in use? What brand and model is your router?
• do you use a wifi mesh system? If so, which one?
• are your wifi channels set to automtic or to fixed channels?