A reboot after changing settings is never a bad idea. When the yellow text has a notice to restart system, a reboot is mandatory.
If you have no ethernet cable connected, please also activate the Standalone option:
The accesspoint redirects all external requests to itself and sets up a default gateway to its IP-adress. Always activate this, if the device is not connected to the internet and if there is no other router connected by LAN-interface. Otherwise the audioplayers (e.g. squeezelite) will not work correctly.