Thank you for using the answers forum! I'm sorry to hear you are having trouble getting a network connection to your Slingbox PRO-HD. I would first like you to take a look at an article from our knowledge base that provides great troubleshooting steps you can take in attempt to resolve this issue.
Here is the link:
Feel free to reply if you are still experiencing the issue after looking over the article.
The Sling Moderation Team