Hey,
Unfortunately, it looks like the server issue since, according to the error message, your server cannot resolve the IP address for Facebook API.
Here is the StackOverflow thread for the same issue and, as it is recommended there, I would advice you to contact your hosting provider and ask them if they can solve the error for you since the error is not code related: https://stackoverflow.com/questions/35271872/facebook-php-sdk-v5-name-lookup-timed-out
Milos