Before starting the below, I suggest that you reboot the SONOS units.
Wire PLAYBASE and give it a few minutes to reconfigure. I expect that the system will work now. Next, in Settings go to Update Network and give the new WiFi credentials. If the PLAY:1 balks about this, temporarily power it down. PLAYBASE will now operate via WiFi. If PLAY:1 did not go along with this, Factory Reset PLAY:1 (do not Factory Reset PLAYBASE) and add PLAY:1 to an existing system— take care not to create a new system.
If you have not already done this, I suggest that you “reserve” IP addresses in your router. You’ll need to consult your router manual for instructions. Address reservation prevents mischief.