What I'm getting from your post, is that you're having problems with the Slingbox ID connection.
In this case and as a first step, I would recommend to perform a hard reset of the Slingbox.
Also, to discard any streaming restriction affecting the connectivity
On the other hand, you can update the router's firmware as well and even use an IP connection instead of the Slingbox ID
If the problem is still the same after that, you can comeback and let us know the outcomes.