Why does my Google Nest Audio disappear from the app?

The short answer

Casting and grouping rely on local discovery messages being allowed. The gadget is usually still online. What's broken is your phone's ability to see it, and that is a network setting rather than a fault with the device.

What's happening underneath

Significant. Voice assistants and casting both rely on discovery messages being allowed across the network.

Source: Manufacturer documentation

Try these, in this order

• • Put your phone on the same Wi-Fi name as the speaker.
• • Use one Wi-Fi name for both bands instead of two separate names.
• • Turn off 'client isolation' or 'AP isolation' on the router.
• • Unplug any old extender and retest before changing anything else.
• • Check the signal where the gadget actually lives, not where you're standing.
• • Move the router off the floor and out of any cupboard before buying anything.
• • Put the gadget and your phone on the same Wi-Fi name.

Setting it up again properly

• • Stand next to your router while you set it up, then move the gadget to where it lives.
• • Put your phone on the 2.4 GHz network name for the setup, or use one name for both bands so the phone can follow.
• • If your router splits bands into two names, turn the 5 GHz one off for five minutes rather than fighting it.
• • Turn mobile data off on your phone during setup — some apps quietly use it and never find the gadget.

When it's worth spending money

Almost never — this is a network-name or isolation setting nine times out of ten.