The main issue is the connection speed. Keep in mind that the Slingbox SOLO needs at least 600kbps in order to work with the SlingPlayer software. If you are using the web-based application, the required connection speed is about 768kbps. The following links will provide you with the requirements for the Slingbox SOLO.
In this case, you must check your Internet connection in order to determine if the available bandwidth is being affected by another user or equipment.