Yeah im now thinking about whether I need to go change everything to our guest network and what a giant pain in the *** that would be. When you're home does that mean you have your phone on the guest wifi? Because most things Bluetooth to the phone and automatically use the same wi-fi when you do setup.
I think life stage matters a lot to what you have connected also. We can add to the list of stuff many may have like some smart lights (control color and dim and stuff from phone and can automate it), TV, thermostat...but then add baby monitors and baby sound machines too. Per baby!
Yeah, so the best practice is always going to be "it depends".
On most WiFi routers, you can create exactly 2 networks, one primary network where all devices can see/talk to each other, and one guest network where the devices are all siloed.
- Device A on primary network can talk to device B on primary network
- Device C on guest network cannot talk to device B on primary network
- Device C on guest network cannot talk to device D on guest network
In this case, you would determine the appropriate network for each device based on anticipated usage. For example, I need my laptop to be able to talk to my storage device and printer, so they all go on the primary network. My kids like to play LAN-connected games on their computers, so those go on the primary network. My water leak sensors only need to connect to the internet, so they go on the guest network.
My cameras are currently configured for live viewing only (no playback), so they only need internet access. If I wanted them to record data to the storage device, they'd need to be on the primary network.
As you pointed out, casting from a phone to a TV can usually be done via Bluetooth, so there may not be a need to connect the TV to the internet at all. If apps like Netflix, Hulu, etc. are loaded directly on the TV (as opposed to a separate device like Firestick or Apple TV), the TV will need internet access, but most likely does not need to be on the primary network.
If you have a more advanced router, you might be able to create multiple networks with various routing rules, but you'll likely need to be pretty skilled to do so.