First, find out which side is broken
Check another device on the same network. If a laptop or another phone cannot get online either, the router or the connection to it is the problem, and nothing on the iPhone will fix it. Restart the router — unplug it for thirty seconds — and if that does not help, the fault is with the line, not with you.
Then check the iPhone on a different network: a friend's, a café's, or a personal hotspot from another phone. If it connects everywhere except at home, the problem is the pairing between this phone and that router, and the steps below are aimed squarely at it. If it fails everywhere, skip ahead to the settings reset.
Turn Wi-Fi off and on, then restart the phone
Switching Wi-Fi off in Control Centre only disconnects it until tomorrow. Use Settings → Wi-Fi instead: switch it off, wait ten seconds, and switch it back on.
If that does nothing, restart the iPhone. It is the least interesting advice there is and it clears more Wi-Fi faults than anything else on this page, because the wireless chip's firmware is reset with it. A force restart goes further when the phone is unresponsive.
Forget the network and join it again
Settings → Wi-Fi, tap the ⓘ next to the network, then Forget This Network, and join it again with the password. This throws away everything the phone remembered about the network — including a stale address or security setting that the router has since changed — and is the single most effective fix for a network that worked yesterday and does not today.
While you are there, check whether Private Wi-Fi Address is on. It is the right default, but a few routers with device-based access controls refuse a phone whose address changes. Turning it off for this one network is safe and fixes those cases.
Check the router's own settings
If only your iPhone has trouble with one router, the router is usually doing something unusual. Mixed security modes (WPA2/WPA3 transition) and band steering that pushes the phone onto a weak 5 GHz or 6 GHz signal are the usual suspects. Giving the 2.4 GHz and 5 GHz bands different names lets you test each on its own.
If Weak Security appears under the network name, the router is using an older encryption standard. Updating the router's firmware and switching it to WPA2 or WPA3 fixes the warning and often the connection with it.
Reset network settings
Settings → General → Transfer or Reset iPhone → Reset → Reset Network Settings. This erases every saved Wi-Fi network and password, Bluetooth pairing, VPN profile and cellular setting, and rebuilds the networking configuration from scratch. Your data, photos and apps are untouched.
It is the right step when the iPhone fails on every network, or when Wi-Fi is greyed out and will not switch on. Our network reset guide covers what you will need to set up again afterwards.
Update iOS
Apple fixes wireless bugs in point releases more often than it says. If a fault started with an update, the next one frequently fixes it — check Settings → General → Software Update, using cellular data or a computer if Wi-Fi is the thing that is broken — updating without Wi-Fi covers both routes.
If you are running a beta, the beta is the likeliest cause. Our beta Wi-Fi guide deals with that case specifically.
When it is hardware
A Wi-Fi switch that stays greyed out after a network reset and an update, or a phone that cannot see any network at all while others nearby can, points at the wireless chip or its antenna. Phones that have been dropped or exposed to liquid are the usual candidates.
A full restore from a computer is the last software step — it rules software out completely. If Wi-Fi is still dead after that, the phone needs a repair rather than more settings.
Frequently Asked Questions
Why does my iPhone say no internet connection on Wi-Fi?
The phone is connected to the router, but the router is not connected to the internet. Restart the router; if other devices are offline too, the problem is the line, not the phone.
Why does my iPhone keep disconnecting from Wi-Fi?
Usually a weak signal at the edge of the router's range, or the router steering the phone between bands. Forget the network and rejoin it, and try giving the 2.4 GHz and 5 GHz bands separate names.
Does resetting network settings delete anything?
It removes saved Wi-Fi networks and passwords, Bluetooth pairings, VPN settings and cellular settings. Photos, messages, apps and everything else stay exactly as they are.
Why is Wi-Fi greyed out on my iPhone?
Restart the phone, then reset network settings. If it is still greyed out after an iOS update, the Wi-Fi hardware has most likely failed and needs a repair.