For years I've had very intermittent use of my Slingbox Pro. Great concept (which is why I bought it in the first place about 3 years ago), but what a pain to watch, even over my local network. Whether over a Firefox plugin or with the SlingPlayer stand-alone software (which I much prefer), the setup would sometimes work, then appear to hang with very slow data transfer.
Here's my setup: The Internet cable connection is in a downstairs office, so the router is located there. The TV, Tivo, and Slingbox are all located upstairs (the main floor) in the living room. Several years ago I bought some inexpensive Powerline Ethernet boxes to get the ethernet connection from the router to the Slingbox. It worked, but was maddeningly intermittent.
So finally last month I decided to take another look at the setup. Since the Powerline boxes were old, I bought two new ones from a different manufacturer from Newegg. You know, maybe the old boxes were the problem, right? Tried the new boxes, same result: sometimes Sling streamed robustly, sometimes the data rate was down to 10Kb/sec.
Last week I really spent some time trying lots of options--different power sockets upstairs, different ethernet cables, and so forth. Then I tried disconnecting other equipment also plugged in upstairs. Bam! The data rate skyrocketed. Okay, let's plug in other items one at a time.
Turns out the wall transformer for my Squeezebox (another really cool device) was making the Powerline ethernet boxes go nuts. Plug the transformer in, data rate goes to zero. Unplugged, datarate high. So I found a different location for the Squeezebox transformer, and now the Slingbox setup works beautifully. I can watch my Tivo content anywhere on the local network, or anywhere in the world via the Internet.
I wish I had discovered the issue years ago.