When I turn on my nexus 7, or sometimes when I wake it up, I have an issue whereby it takes a few minutes for it to properly establish a WiFi connection. It detects the wireless router, but the WiFi symbol is showing in white rather than blue. The connection also drops out intermittently in the same way. The device is set to keep WiFi switched on when it's sleeping so I know it's not that. Is there anything else I'm not doing that I should be doing?