I've recently noticed that a new device shows up as available to cast to from my android phone when I'm logged on to our home Wi-Fi. It's an LG Sk8100 TV, but as we own no such TV. I'm assuming it's the neighbour's.
Since our Wi-Fi is WPA2-PSK AES protected, and I have not shared the key with the neighbour, I'm worrying that our network is compromised.
Strangely though, checking the device list in the router, no TV shows up in the DHCP Client list or wireless connections for either 5Ghz or 2.4Ghz networks. The only connected devices are my desktop PC and my android phone.
So why can I cast to this mystery LG TV when I connect to our Wi-Fi, while no such TV seems to exist in the attached devices list of the router?
The TV does not show up if I disconnect Wi-Fi, or if I leave our apartment. It only shows up when connected to our Wi-Fi. If I try to cast to it, the connection times out and fails. I speculated that it was some Google thing tied to location, but it's still there with location tracking off on the phone.
It also seems that the only app that can "see" the phantom TV is YouTube for some reason. That is, other cast-enabled apps, like Netflix or Chrome, are not able to see the TV. Moreover, it only shows up in the YouTube app on my phone (a Huawei P20), so not on the desktop or my wife's phone.
I have now conducted another test where I set the router in MAC-adress whitelist-mode, and the TV is still there. So there is something really strange going on.
I'm leaning towards this being some Google software quirk rather than an attack, but maybe someone here recognizes the issue and has input.
One thought, could the TV show up through my ISPs CG-NAT? Or in the WAN above the router in some way?