SQL Server is touchy about the names. Depending on how it's configured you may or may not be able to just use an IP address like you're using in the connection string. When I'm faced with this, I first try to make sure I can connect to the server using SQL Management Studio. First try it with the IP address like in your connection string. If it doesn't connect, you'll need to check the actual name of the server and try that. Then if Management Studio can connect, you know you're good, and you can paste the name back into your connection string.
Also, just a thought as I look again at your connection string. It looks like you have both integrated security (which refers to logging in with your existing Windows account), as well as a username/password. I'll need to check, but I think you shouldn't have both. (I might be wrong there, though.)