This is very sudden in the past day and as far as I know, no settings have been changed on the Mac at all. Has anyone encountered this before?
At least 84 people at the last count Did you not check the forum before posting this ? There are at least 12 different posts on this subject in the last 24 hours.
This thread is Sling admitting there are problems with their servers at the moment. https://community.sling.com/thread/4005?tstart=0