My laptop is connected to wifi and i can use internet when i plugged in the charger, but when i unplugged it, my laptop still connect to wifi but i cannot access to internet, it says i need to fix proxy setting.
I don't see the econnection with the power issue unless the battery is pretty flat but if you need to fix the proxy setting this is how it's done.
Go into Control Panel>Internet Options?Connection tab>LAN button. Remove the tick from the Proxy box and put one into the Automically detect settings. OK your way out and restart the machine. That should do it.
If you're using Windows 10, you find the Control panel by pressing the Windows key and R together. In the Run box that appears, type
then hit teh Enter key.