The short answer
The phone is fine, since it works elsewhere. Look at the router: a full DHCP address pool, MAC filtering, band steering, a WPA3-only security setting, or a stale saved network on the phone. Forget the network on the phone and check the router’s address pool first.
A phone that connects everywhere except at home is telling you something useful: its radio, its drivers and its Wi-Fi stack all work. The problem is in the interaction between that phone and your specific router, and there is a short list of settings that cause it.
Start with the two-minute checks
Forget the network and rejoin
On the phone, forget the home network entirely, then rejoin by typing the password. A stale saved profile with an old password or old security settings is the most common trivial cause.
Toggle airplane mode
It resets the radio and clears a stuck association. Thirty seconds of effort before anything more involved.
Restart the router
Not because restarting is magic, but because it clears the address table, which matters for the cause described below.
Check whether other devices work
If everything else is fine and only this phone fails, the cause is device-specific. If several devices have started failing, it is the router.
Cause 1: the address pool is full
Routers hand out addresses from a pool, often as few as 50, and each device holds its lease for a day or more even after it leaves. A household with phones, laptops, a TV, a console, smart bulbs, plugs, speakers and visitors’ phones can exhaust a small pool. When it is full, a new device associates with the network and then fails to get an address, which looks exactly like a password problem.
The symptom to recognise is a phone that says Obtaining IP address, then Authentication problem or Unable to join. Fix it by enlarging the DHCP pool in the router settings, and by shortening the lease time to a few hours so that departed devices release their addresses sooner.
Cause 2: MAC filtering or a block list
Many routers include parental controls or device blocking, and it is easy to block a device by accident, especially in an ISP app where a tap on the wrong row blocks a device permanently. Check the router’s list of connected and blocked devices, and look for an entry matching your phone.
Modern phones complicate this by using a random MAC address per network, for privacy. If you have a MAC filter allow-list, a phone that rotates its address will be refused. Either disable private or randomised MAC for your home network in the phone’s Wi-Fi settings, or add the current address to the allow-list, or stop using MAC filtering, which provides very little security anyway.
Randomised MAC addresses are also why a phone sometimes stops working after an OS update. The update rotates the address, and your router’s filter, reservation or parental control rule no longer matches. Setting the network to use the device MAC for your home network only is a reasonable compromise.
Cause 3: security mode mismatch
If the router is set to WPA3 only, older phones cannot join at all. If it is set to WPA2/WPA3 mixed mode, a small number of devices handle the transition badly and fail intermittently. WPA2 only is the most compatible and slightly less secure.
Try WPA2/WPA3 mixed first. If the phone still fails, set WPA2 only temporarily as a test. If that works, you have identified the cause, and you can decide whether to keep compatibility or upgrade the device.
Cause 4: band steering
If the router broadcasts one name for both bands, some devices fail to associate cleanly, particularly when the signal is marginal and the router is pushing the device onto a band it cannot hold. Splitting the bands into two names is a quick test: if the phone joins the 2.4GHz network without trouble but not the combined one, steering is your culprit.
Cause 5: the network name or password itself
- Special characters in the network name or password cause problems on some devices. Emoji, accented characters and certain punctuation are worth eliminating as a test.
- A hidden SSID is a frequent cause. Hidden networks are not more secure and they cause connection problems on many devices. Un-hide it.
- Two networks with the same name in range, perhaps from an old extender still plugged in somewhere, will confuse devices badly.
- A very long password pasted from a manager can pick up a trailing space. Retype it manually once as a test.
Cause 6: something on the phone
Even though it works elsewhere, a phone-side setting can be involved:
- A VPN or private DNS setting that fails against your home network’s DNS, making the connection appear dead even though it associated fine.
- Reset network settings on the phone, which clears all saved networks, Bluetooth pairings and mobile settings. It is a bigger hammer than forgetting one network and it does resolve stubborn cases.
- A captive portal check failing, where the phone decides the network has no internet and refuses to stay connected. This happens if your router’s DNS is misconfigured or a filtering service is blocking the connectivity-check domain.
If your phone connects but shows no internet, that is a different problem from failing to connect. No internet with a successful connection points at DNS, at the router’s own uplink, or at a filtering service, rather than at Wi-Fi authentication.
Narrowing it down efficiently
Create a temporary second network on the router: a new name, WPA2, 2.4GHz only, short simple password, no filtering, on a clear channel. If the phone joins that, you have proved the phone is fine and you can then change one setting at a time on the main network until it fails. This is much faster than guessing, and most routers let you create a guest or secondary network in a minute.
Why does my phone say authentication problem with the right password?
Most often the router could not give it an address, not that the password was wrong. A full DHCP pool produces this exact message on Android. Enlarging the pool usually fixes it.
Should I turn off private MAC address?
For your home network only, it is reasonable, particularly if you use MAC-based reservations or parental controls. Leave it enabled on public networks, where it provides real privacy benefit.
Does hiding my network name make it more secure?
No. The network is still detectable, and hiding it causes connection problems on many devices while providing no meaningful protection. Use a strong password instead.
Will resetting network settings on my phone delete anything important?
It clears saved Wi-Fi networks and passwords, Bluetooth pairings and mobile network settings. Nothing else is affected, but you will need to rejoin networks and re-pair devices.
Why did it stop working after a software update?
Updates can rotate the randomised MAC address, change the default security negotiation, or reset a saved profile. Forgetting and rejoining the network resolves most of these.
The efficient order
Forget and rejoin, then check the router’s DHCP pool and blocked device list, which together account for most cases. Then test WPA2 only, split the bands, and un-hide the network if it is hidden. If you are still stuck, create a simple temporary network to prove the phone works, then change one main-network setting at a time until the failure reappears.
