Chromecast can only access 2.4GHz WiFi network. But your mobile devices or PCs that are on 5GHZ network or on Ethernet can still find and connect to this Chromecast device, as long as your devices and Chromecast are connecting to the same router.
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Jun 26, 2020
Re: Chromecast Firewall Settings 12-05-2013 10:28 AM - edited 12-05-2013 10:30 AM Chromecast service discovery requires both the Chromecast and the client device to be on the same layer 2 segment (similar to Apple devices).
Apr 04, 2019
22 Things You Didn't Know Your Chromecast Could Do Turn your Chromecast to Guest Mode in the device settings, and anyone with a Google Cast Ready app that's open within about 25 feet of the Chromecast will be able to cast once the option shows up Chromecast Firewall Settings - Page 2 - Airheads Community