Thank you for posting in the Slingbox Answers Forum! That's a great question.
SlingPlayer does not auto adjust to work with your Internet speed. However, manually switching the Quality in SlingPlayer to SQ should allow you to connect to the Slingbox without an issue.
Please take a look at the article below:
This article only refers to connecting from a mobile device. However, doing the same thing will work when connecting in Watch on Slingbox.com.
The Sling Moderation Team