Hotel Wi-Fi almost always enables client isolation, which means your phone can't "see" your Chromecast even though both are connected. This guide explains why it happens and how LocalCast works around it using phone hotspots and DLNA.
Hotels enable client isolation to stop guests from snooping on each other. It also blocks device-to-device discovery, which breaks Chromecast, AirPlay and DLNA at the same time. Your phone and TV are on the same network but can't talk to each other.
Open LocalCast, go to the DLNA source. If the hotel TV shows up, great — cast normally. Skip to step 3.
If DLNA doesn't work, turn on your phone's hotspot. Connect both the Chromecast and the hotel TV (or any streaming dongle) to the hotspot. Re-launch LocalCast.
With every device on your hotspot, isolation is out of the picture. LocalCast finds the TV and casts like you're at home.
Client isolation. The hotel Wi-Fi puts each guest in their own virtual network, so your phone can't reach the Chromecast even though both are connected. Use your phone's hotspot instead, or a travel router with its own Wi-Fi.
LocalCast + a phone hotspot = casting anywhere. Free forever.