I understand that you are having some issues with the SlingPlayer for iPhone / iPad since you are not able to get the high quality.
The current connection speed is not good enough if you have in mind to stream the high quality signal. The following links will provide you with all the information about the requirements:
So, if you want to get a better video quality you'll need to increase your current connection speed since your current connection speed is not good enough at all. Finally, I encourage you to check the following third-party link in order to know how to adjust the router settings:
Hope this helps.