Since your Slingbox is being located but you are not able to connect, the issue that you are having might be caused by a security setting or firewall on your computer. You can try disabling the firewalls on the Antivirus and if the issue persists, try downloading the SlingPlayer Desktop to configure it that way.
Use this link to download the application,
Once you finish with the installation, try connecting to your Slingbox using the Web-Based SlingPlayer. If the issue persists, we recommend you to use another computer and to determine what is causing the issue.
I hope it helps!