I was having trouble controlling my 350 with the onscreen remote. I had to reset my 350 and I used the new desktop setup program on my PC to reconfigure it. After numerous attempts, I finally was able to control my DVR remotely in the setup program.
Once I go to the website to watch it though, I get the P-1 error and it can't communicate with the box.
How can I get the website to recognize my box again after the reset?
I see that you are having a hard time viewing once you have completed the set up. You can try to delete the Web Plug In for Slingplayer. Once you have done so, reinstall it. Perform a hard rest once more and continue with the set up.
Below are some helpful links:
Sling Media Support Team