Two questions decide most of what follows, and neither costs anything to answer. Does the phone fail on this one network, or on every network it tries? And does this network fail for every device in the building, or only for the phone in your hand? Google's Wi-Fi troubleshooting page splits the problem in exactly that place: if other devices can use the network, the problem is most likely with your phone, and if your phone can connect elsewhere, the problem is most likely with the network.
Put a second device on this network. Then take the phone elsewhere: a neighbour's network, a cafe, another handset's hotspot. Google reads the result three ways.
The third gets argued with. A full Wi-Fi icon means the phone and the router are talking, not that the line behind them works. Calls that fail indoors are a different job: routing calls over Wi-Fi is a carrier feature with its own switch, in turning on Wi-Fi calling on Android.
A saved profile goes stale when the router's password changes, or a character went in wrong. Google's fix is to delete and re-add it: Settings, Network and internet, Internet, Saved networks, tap it, Forget, rejoin. Retype with the characters showing, since Samsung notes that Wi-Fi passwords are case-sensitive. Or have a still-connected device show the network as a QR code and scan it: scanning QR codes on Android.
Public networks want a sign-in page completed first. When it never appears, Google says to look for the sign-in notification, then open a new page in a new window, then forget the network and rejoin.
One cause is not radio at all. Google states that an incorrect date and time can cause Wi-Fi connection problems, fixed under Settings, System, Date and time, Set time automatically. The same wrong clock stops the Play Store, and that guide explains what it is checked against.
The Android Open Source Project explains why phones hide the hardware address: because these MAC addresses are transmitted without encryption, they can be captured and used to potentially track a user's location. Android 10 and higher use a randomised address by default, one per network. AOSP adds that it is persistent, stays the same until a factory reset, and is not re-randomised if you forget and re-add the network. Seeing two different addresses is the feature working, not a fault.
It bites where a network decides who gets in by address. AOSP names those cases: persistent addresses are necessary where networks rely on that persistence, for example to remember a device and let you bypass the login screen, or to enable parental controls. An allowlist holding only the hardware address will not admit the phone, and Google's tip is to enter both.
Know the trade first: switching randomisation off gives that network a stable identifier for your phone, the tracking the feature prevents. Do it on a network you own or one whose operator asked for it, not a hotel. An allowlist holding only the hardware address will not admit the phone, and Google's tip for parental controls is to enter both addresses. AOSP places the option in the Network details screen; operators who require it publish Privacy then Use device MAC on a Pixel, Advanced then MAC address type on a Galaxy.
Bands do not reach equally far: Google states that the 2.4GHz signal travels a greater distance than the 5 or 6GHz signals. Who chooses gets told wrong. On Google's own hardware one name covers every band, and band steering will attempt to guide devices to the band with the best performance for each. Attempt is the word, because Google also says your device decides which band to connect to.
Much of what you see is therefore not a fault. Google describes Wi-Fi points as transitioning you to the best point as you move about, and a handover stalls a video for a moment. Treat it as a fault only when the connection does not return by itself, or drops while the phone sits still. Google's interference list is short: microwaves, cordless phones, baby monitors, and walls of concrete or metal.
If what fails is a television, the band split becomes a discovery problem, and it is the first suspect in screen mirroring that never finds the TV. Wireless Android Auto carries the screen over 5GHz Wi-Fi after a Bluetooth handshake, which is why a head unit that never appears is a Wi-Fi problem. Splitting the bands into separate names is a router fix, not a phone one.
Google's first three moves: turn Wi-Fi off and on, turn airplane mode on and off, restart. Then install anything pending, since updates can bring improvements that help fix issues. Updating your Android version has the Pixel and Samsung paths. Safe mode then tests for a rogue app: Google says that if Wi-Fi works there a downloaded app is most likely the cause, and if not, the problem is likely the network. Airplane mode turns itself on in safe mode, so switch it off first.
On a Galaxy, a common random disconnect is a feature. Settings, Connections, Wi-Fi, More options, Intelligent Wi-Fi holds Switch to mobile data, which Samsung describes as switching whenever the Wi-Fi connection is unstable, and Switch to better Wi-Fi networks. Turn both off while testing. Pixel owners look for the same switch under Adaptive connectivity and find nothing: that one is about 5G. Google also notes that some devices, such as the Pixel 7a, cannot run a hotspot and Wi-Fi at once.
A network reset is the last move on the phone side, and it destroys things, so the losses come first. Samsung's wording is that the Wi-Fi information, mobile data and Bluetooth connection are reset. In practice that is every saved Wi-Fi password and every Bluetooth pairing on the phone. Apps, photos and messages are untouched, but there is no undo.
So write the passwords you need down first, somewhere that is not this phone, starting with the ones you cannot read off a sticker.
Then, and only then, the paths. On a Pixel: Settings, System, Reset options, Reset Bluetooth and Wi-Fi, then Reset settings. On a Galaxy: Settings, General management, Reset, Reset Wi-Fi and Bluetooth settings, then Reset settings. Rejoin your home network first, so you learn straight away whether anything changed.
Three patterns make the phone a witness rather than a suspect. Everything in the building drops at once. It happens at the same time daily. Or it began the week a router firmware update landed, or the provider changed.
What proves it is the test from the top: a second device on this network, this phone on another. If the second device fails too, restart the line Google's way, unplugging the router and modem power cords for 15 seconds and waiting until the lights on both are right. If they are not, Google says you could have an issue with the modem, router or internet connection.
Past that it is somebody else's equipment. On a network you do not own, the only thing here you can change is the phone's per-network MAC setting; the rest belongs to whoever runs the place. Google's own troubleshooting ends by pointing at three parties, the internet service provider, the router manufacturer and the network administrator, and says there could be a service outage or they could need to reset your connection. Working out which one to contact is the whole job, and the two questions at the top are what answer it.
A full Wi-Fi icon proves the phone and the router are talking, not that the line behind the router works. Google's guidance is that a phone which connects but gets no internet points at the internet connection. Test a second device on that network, and on a public one look for an unfinished sign-in page.
Only for a network that needs it, such as one with a device allowlist or parental controls. Android has used a randomised MAC address by default since Android 10, because the address travels unencrypted and can be used to track a device. The setting is per network, so changing it for the office leaves other networks private.
The one named Reset Bluetooth and Wi-Fi on a Pixel, or Reset Wi-Fi and Bluetooth settings on a Galaxy. Samsung's wording for it is that the Wi-Fi information, mobile data and Bluetooth connection are reset, and in practice that means every saved Wi-Fi password and every Bluetooth pairing on the phone. Apps and photos are untouched, and there is no undo, so write the Wi-Fi passwords down before you run it.
Yes. Google describes a mesh system as transitioning you to the best Wi-Fi point as you move through the home, and says the device itself decides which band to connect to. A brief stall during that handover is the system working, not a fault.
Work on that phone. Forget the network and rejoin with the password visible, since Wi-Fi passwords are case-sensitive. Install any pending update. Then try safe mode: if Wi-Fi holds there, a downloaded app is the likely cause. A network settings reset is last, because it erases every saved Wi-Fi password and Bluetooth pairing on that phone.