Why can my phone not find the TV when I try to cast?

Casting requires the phone and the TV to be on the same wireless network. If the TV is on the 2.4 GHz network and the phone on 5 GHz, or the phone is on mobile data, they cannot see each other. Put both on the same network name.

Can I put the TV on the guest network?

Better not to. Guest networks are built so devices cannot talk to each other, which stops casting and remote-control apps from working. Connect the TV to the home's normal network name.

My Chromecast keeps restarting, why?

Usually the power. If the power cable is plugged into the TV's USB port it gets too little power and switches off when the TV is off. Move it to the supplied adapter in a wall socket.

Should I factory reset the TV?

Save that for last. A reset removes every app and every sign-in to SVT Play, Netflix and the rest, and the channel scan has to be redone. A restart and a fresh Wi-Fi connection solve this in almost every case.

Smart TV or Chromecast will not connect to Wi-Fi

A TV or Chromecast that cannot reach the internet has usually ended up on the wrong wireless network, or lost the connection after a power cut. Restarting the TV and the router in the right order fixes it for most people and takes five minutes. If you are casting from a phone the rule is simple: the phone and the TV have to be on the same network name.

The router is the box with lights that gives you internet. Many homes have two network names coming from that one router, and one of them has 5G or 5GHz in the name. Older TVs can only use the other one, the 2.4 GHz network.

Try this first

Check that the internet works in that room. Pick up your phone, turn off mobile data and open a web page. If nothing loads, the router is what to look at first.
Restart the TV or Chromecast. Unplug the power for 30 seconds and plug it back in. At the same time, unplug the router's power for two minutes.
Find out which network name the TV is using. On a Samsung TV: Settings > General and Privacy > Network > Network Status. On LG: Settings > Network. On Sony and Philips models with Google TV: Settings > Network and internet.
Connect the TV again and type the Wi-Fi password yourself. It is usually printed on a label under the router. The password is case sensitive, so capitals and lower-case letters have to match exactly.
If you are casting, turn Wi-Fi on for the phone and check it is on the same network name as the TV. Casting does not work over mobile data.

If that did not help

Put the TV on the 2.4 GHz network. If the names are for example Hemma and Hemma_5G, pick the one without 5G. It reaches further and more TVs support it.
Run a network cable to the TV if it has a socket for one. That settles the connection permanently and gives a steadier picture.
Chromecast: check that it is pushed fully into an HDMI socket and that the power cable goes to a wall socket using the supplied adapter, not to the TV's USB port.
Update the TV's software. On Samsung: Settings > Support > Software Update. On Google TV: Settings > System > About > System update.
As a test, move the TV and the router closer together. If it works at close range the issue is coverage, and an extra access point or a cable is the right answer.

If the TV lists no wireless networks at all, or drops the connection every evening, it is worth going through it with someone. Ask us and we will look at the TV's network menu and the router's network names at the same time.

After you change router

A new router from your provider almost always arrives with a new network name and a new password. The TV then keeps looking for a network that no longer exists and sits there without internet even though everything else in the home works. Open the TV's network menu, choose the new network name and enter the new password. The same applies to a Chromecast, which you reconnect through the Google Home app on your phone.