@nolramlb wrote:
since you already done a factory reset . how about trying software repair using Xperia Companion
also check you router settings, and configuration and match with xperia z3 compatible netwokrs http://developer.sonymobile.com/downloads/whitepapers/xperia-z3-d6603-d6633-d6643-d6653-d6616-white-...
Adding to what nolramlb wrote.....
Another question, is the issue just at home, or do you not see WiFi networks when you are near public WiFi hotspots? If you see and connect to WiFi hotspots outside your home, then you can check your home router. One trick is to pick a specific WiFi channel instead of Auto...try a lesser used one (check router and local Internet provider for info). This will mean less competition for your phone/router combo with other wifi routers in use in your area.
Try running the LAN/WiFi tests in Settings --> About phone --> Diagnostics. Go Tests tab and scroll down to WLAN/WiFi. Tell us what the test results are.
Another method...recommended by Sony tech support person I spoke with is:
Find and tap Phone.
Enter *#*#7378423#*#*.
Tap Service tests > select the service you want to test.
And test the WLAN.
Please let us know the test result.
While doing a software repair is never fun, it's the best way to get the phone back to it's intended operation. Check which applications are constantly polling your phone connectivity (pretty much all of them), and determine whether it's a newly added application that may be causing your trouble.
When all else fails -- and especially if the WiFi tests fail -- contact your local support.
Good luck
