I hit the same problem, as have others (see some of the more recent threads).
In my (and other) case, it appears to be an issue with Comcast - with my TV connected through a T-Mobile hotspot, I was able to access the store and download apps. However, with the TV connected through my Comcast ISP, I got the same "Network Error (2)".
Are you also connected through Comcast as your ISP?