If the "device" your referring to is the Slingbox.
Might want to do a factory reset of the Slingbox http://support.slingmedia.com/get/KB-005036.html
If the "device" your referring to is the router
Then you can go to http://portforward.com for help setting up port forwarding to allow access to your Slingbox from the internet.
I am experiencing the same problem here. This is a Slingbox Classic which I have reset by holding in the reset button for 10 seconds, and it went through its blinking light routine until both the network and the power light were steady green, so I know it is reset.
I see that the "older Slingboxes" are listed as being supported by the web client at watch.slingbox.com as well as legacy versions of Slingplayer. On both MacOS 10.7 Lion running supported versions of Chrome, Safari, and Firefox (I have tried all three), as well as Windows 7 x64 running supported versions of Chrome, IE, and Firefox (I have tried all three), I am unable to get the Slingbox to complete setup. I am strictly following the support recommendations for "legacy slingboxes" in the chart at http://support.slingbox.com/get/KB-2000121 as well as the browser recommendations for watch.slingbox.com at http://support.slingbox.com/get/KB-2000075.html . On all of the web browsers, the system gets to "Locating your slingbox on the network..." and then it shows the "Slingbox Directory" screen where it finds my Slingbox just fine:
Dan's Slingbox (unconfigured)
I click on this and it brings me to an "initializing" screen,
Then it proceeds to "Welcome" Click Start to complete your Slingbox setup", and I click start. It continues just fine until it scans for composite video signal, whereupon the plugin crashes with a "Slingplayer has crashed" yellow window.
On the Legacy Player client, I get a bit more information:
Here's the answer to my, and presumably also the OP's, question. See the new thread I created -- https://community.sling.com/message/95908#95908
I simply needed an even OLDER version of the software than what is provided on the Legacy site, and in fact that version 1.5 was it! Version 22.214.171.1248-US works perfectly. I found that version here: http://placeshiftingenthusiasts.com/how-to-install-both-slingplayer-v2-0-4-and-v1-5-on-same-computer/ I should point out that unlike the information at http://support.slingbox.com/get/kb-5000207.html implies, this was not because I had very old firmware -- the Slingplayer 2.0.4522 and the others I tried all reported that I already had the latest firmware.
Slingbox webmasters, can you please update the web page at http://support.slingbox.com/go/downloads and also at http://support.slingbox.com/go/slingplayer-windows to make this older version available for those of us with very old devices that don't seem to setup properly with the web client?