Nokia Lumia 920 - I am losing a network connection on my Lumia every now and then. What can I do?

Try changing the network connection to 3G. Go to Settings, tap mobile network, and set Highest connection speed to 3G.

Check updates: Your phone automatically checks for updates on a weekly basis. If you have a Wi-Fi connection, your phone downloads the update once available. To change the settings, or manually check for updates, just tap Settings > Phone Update.