Unfortunately the problem hasn't simply resolved itself. I'm still getting the same "Failure to connect" error during the "Starting..." phase when launching the Slingplayer app on my Android device.
The "Locating" stage seems to complete without a problem, so I'm not sure why this problem suddenly developed.
Just to reiterate, my home broadband/router setup has not changed.
I wonder if there might be a conflict with another Android app. I might try removing a couple of UPnP apps on the offchance.
Otherwise, I'm pretty stumped.
Well in desperation I tried a factory reset of the HDS-600RS.
Suddenly the Slingplayer app seems to be working again.
Bit unsatisfactory as I haven't got to the bottom of the problem and can't be sure it won't recur tomorrow.
I also get a warning that "my Slingbox model is not supported for Android" which is a little off-putting seeing as Android support is specifically mentioned on myechostar.com
Incidentally, I'm using a Samsung Galaxy S II running Android 2.3.3.
I'm happy again for now and will report back if things go wrong again. Maybe the recent 117R release meant I need to perform a factory reset (??).
Thanks for taking the time to enquire.