If I have a guest network on my router and connect all Alexa plugs, echo devices, Alexa fire tv and lights to it, how do I deal with the issue of being able to airplay to my tv and things like playing from Spotify on to echo devices? My understanding is this requires the devices to be connected to the same wifi network as the device to work. As my other primary network is for all laptops, smart phones and things like that that I want separate.
To keep your network segregated and still have access to your devices, you need a router, switches and APs capable of doing VLANs. Then you would need to setup access rules in the firewall. Most standard home routers are unable to do this unless you are using custom firmware. I decided to use a separate gateway/firewall, managed switch and access points from Ubiquiti. I have four VLANs configured for trusted, IoT, cameras and guest devices. This can be more expensive than using a basic router, but you have more control over your network if you are inclined to put the time into configuring the network.