Thanks for your post. We would like to apologize for the inconvenience you've gone through. This error message may appear if the TV is not connected to the Internet. If the issue is not resolved after following the troubleshooting steps, update the TV software. Software and driver updates for your Sony product are available online.
In addition, please reset and update your modem / router.
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I had the same problem on my bravia KDL- 43WD750. Nothing helped me to solve it. Many times resetting either modem or tv, factory settings etc.
If your router supports WPS then you have luck. Just turn WPS fucntion on by simply pressing the button on the router, and connect via WPS on your TV then refresh the internet content. Afterwards you can connect to wifi normally by just scanning the wireless connections. In this way the WPS fucntion will be turned off.
It worked pretty fine with me. Eventually I reset both the modem and the tv. It worked still fine.
Note: If you have to connect via WPS again then you have to touch the button and perform the further instructions as mentioned above.