My computer says i have internet access but it wont work?

[569]

I have desktop that is currently connected to my router with a wireless adapter. Everytime i start my computer i have problems connecting to the internet. It says i have internet access but when i try to go to a website nothing happens, All my other devices connected to wifi work perfectly fine tho. Samething with other programs like steam and origin. But sometimes it randomly goes on and off. I have never seen pattern of on/off like this before. It goes off for an hour then goes on for like 4 hours. It goes on for 30 seconds but then goes off for 30 seconds. Sometimes i think it has a mind of its own. Keep in mind like i was saying, it shows that i have internet access at all times. Does anyone know what the problem is?