Client isolation can prevent devices on the same wireless network from communicating directly. Internet video may still play while a phone remote or casting feature cannot find the screen. That difference points toward local policy rather than media capacity.
Compare local and internet tasks
Open an ordinary internet service on each device, then test the local control separately. Two successful internet connections do not prove that peer-to-peer discovery is allowed. Note which function fails instead of calling the entire Wi-Fi connection broken.
Check the intended network role
Guest, office and public networks may isolate clients deliberately. Ask the administrator about supported casting arrangements. Do not weaken a shared network's boundary to make one app's remote feature work.
Use trusted-device placement
On a home network you manage, place trusted devices on an appropriate supported network segment. Keep visitors and untrusted equipment isolated as intended. Follow the router's documentation rather than turning off every protection.
