The short answer
The phone and the TV must be on the same network and able to talk to each other. A phone on 5 GHz and a TV on 2.4 GHz often cannot see each other if the router keeps them apart, and a device on the guest network never will, because guest networks isolate clients by design.
Casting relies on device discovery across your local network. Almost every failure is a network visibility problem rather than anything to do with the app or the television.
The checks that fix most cases
1. Same network, genuinely
Not just “both on the Wi-Fi”. Check the exact network name on both devices. Common traps: the phone on a guest network, the TV on a network with a “-5G” suffix while the phone is on the 2.4 GHz one, or the phone quietly on mobile data because the Wi-Fi dropped.
2. AP isolation
Also called client isolation or guest mode. It prevents devices on the network from communicating with each other, which is exactly what casting needs. It is on by default on most guest networks and occasionally on main networks. This is the single most common cause when everything else looks correct.
3. Band separation
Some routers keep 2.4 GHz and 5 GHz clients from seeing each other, particularly when the bands have separate names. Putting both devices on the same band is a quick test.
4. IGMP snooping and multicast
Discovery uses multicast traffic. Routers with IGMP snooping misconfigured, or with multicast filtering enabled, break device discovery while leaving normal browsing perfectly fine. If your router has these settings, try toggling them.
Working through it
Confirm the exact network name on both devices
Read them, do not assume. Move both to the same network, same band, main network rather than guest.
Restart both devices and the router
Power cycle the TV or streaming device at the wall, restart the phone, and unplug the router for 60 seconds. Discovery caches go stale and a restart clears them.
Turn off AP isolation
In the router’s wireless settings, look for AP Isolation, Client Isolation or Guest Mode and disable it on the network both devices use.
Turn off any VPN on the phone
A VPN routes traffic away from your local network, which usually breaks discovery entirely. This catches people out constantly.
Clear the casting app's cache
On Android, clear the cache for Google Play Services and the Home app. On the TV side, restart the streaming device fully rather than putting it to standby.
Check the app supports casting at all
Some services deliberately block casting for licensing reasons, and others removed it. If one app cannot cast while others can, that is the explanation rather than your network.
Turn on your phone’s mobile hotspot, connect the TV or streaming stick to it, and try casting from a second phone also on that hotspot. If casting works there, your home router’s settings are the problem, and AP isolation is the first thing to check.
Frequently asked questions
Why does the cast icon not appear at all?
The phone cannot discover any target, which points at network isolation, a VPN, or the devices being on different networks. It rarely indicates a fault with the television.
Can I cast if my phone is on 5 GHz and the TV on 2.4 GHz?
Usually yes on a single combined network, but some routers separate the bands so clients cannot see each other. If casting fails, putting both on the same band is a fast test.
Why does casting work but keep stopping?
Usually weak Wi-Fi at one end, or the phone sleeping and suspending the connection. Check signal at the television and disable battery optimisation for the casting app.
Does a VPN stop casting?
Almost always. The VPN takes traffic off the local network, so the phone can no longer discover or reach the TV. Turn it off to cast.
Check both network names, then look for AP isolation. Between them they explain nearly every casting failure.
