One of the biggest improvement on Android 4.4.3 release is Wifi connection.
Especially at 5G band. My router is located in living room.
When my Nexus 7 connected with Wifi 5G in the same room, the signal strength is very good. The problem is when I move to the room with two walls distance, connection lost.
It is no problem when it is working on the 2.4G band.
After this Android 4.4.3 upgrade. The problem solved.
See, the signal icon is full.
If your Nexus 7 has same problem as mine, go to upgrade to Android 4.4.3.