Simply so, why do I have 5 bars but no internet?
It's entirely possible to have 5 solid wireless bars but no internet access if there is a problem not related to wireless. First check the lights on your router to see if any are indicating a problem. If a problem is indicated, check all the wires to make sure they are connected properly at both ends.
Beside above, why do I have full signal but no internet? It could be due to broken cables, service disruptions, or just about anything else that's not within your control. That said, it's important to know if the problem lies with your Internet provider. For this, check if the “Internet†light on the modem is working. Ideally, the power and DSL lights should be turned on.
Besides, why is my WiFi not working but I have three bars?
First, reboot your router (just unplug the power cord). Try WiFi again. If you still have problems, WEP encryption and/or old router firmware become the most likely culprits. Lots of people are having this problem, including myself.
Why is my phone not working even though it's connected to WiFi?
If your Android phone won't connect to Wi-Fi, you should first make sure that your phone isn't on Airplane Mode, and that Wi-Fi is enabled on your phone. If your Android phone claims it's connected to Wi-Fi but nothing will load, you can try forgetting the Wi-Fi network and then connecting to it again.