Why does my WiFi work on some devices but not others?

When most devices work and one does not, the network is fine and the difference lies in what that device supports or how it has been treated.

Band support is the most common explanation. Older devices and many smart home products connect only on the lower frequency band. If your router presents both bands under one name, the device may be unable to join at all, or may join unreliably. Separating the bands into distinct network names, at least temporarily, makes this immediately obvious and is often the whole fix.

Security standards are the next candidate. Newer routers may default to a modern encryption standard that older devices do not implement. A compatibility or mixed mode allows both, at a small security cost, and is usually necessary in a household with a range of device ages.

Access restrictions cause the same symptom without any device fault. Address filtering, guest network isolation, and parental controls all block specific devices by design, and it is easy to forget a rule added months earlier. The router client list will show whether the device is being seen and rejected rather than not seeing the network at all, which is a useful distinction.

A saved network with an outdated password is a frequent cause after a password change. The device keeps trying the old credential and reports a generic failure. Forgetting the network on that device and joining fresh resolves it.

Finally, some routers impose a client limit, and inexpensive models can be surprisingly low. In a household with many connected devices, a new one may simply be unable to get a slot until something else disconnects.