A peculiar thing has started happening today and I can't get to the bottom of it. My mrs' Xperia Z3 has started taking nearly 100% of the bandwidth of our router, to the point where pings don't even get through at times. As soon as I disabled the wifi on the phone, everything works as it should again. It even affects traffic that doesn't even require going via the internet; chromecast and file transfers. I've checked the wifi data usage on the phone and nothing stands out, just as soon as the wifi is enabled, the up and download indicators are constantly active on the screen and the network grinds to a near standstill. She says she hasn't had any recent updates to the phone or any apps, she has very few downloaded apps on there anyway. I've tried any combination of devices on the network, no matter what, the phone has the same effect. Even stranger, it slows the phone's internet access in the same way as other devices. I personally have a Z3 Compact and haven't had any of these issues on our network, and before today neither had she. Any ideas? (Naturally I've tried restarting every single device concerned)
Sounds to me like you've got some malware on the device which is eating up your bandwidth for nefarious, spammy purposes. Factory reset time, methinks!
That's what thought may be the case, however something peculiar has happened once again. A few hours after it grinding the network to a halt, the phone notified us of an Android system update. I set it to download (at a much, much reduced rate to normal) and let it sit there for a while, when the download finished the network was completely fine again! It hasn't installed the update though so I don't see how that could make a difference, and the update was nowhere near big enough to justify the amount of time it held everything up. I did find I could restrict all background data and the issue go away, but obviously that had its drawbacks in terms of notifications and the like. Installed the update and now all is fine.
