Why is my Wi-Fi only Xperia Z3 Compact taking down my internet?

[AC Question]

I recently purchased a Sony Xperia Z3 Compact, Wi-Fi only (i.e. no phone). When I turn it on, within minutes my entire internet connection in the house drops. Normally, the connection is fine with two desktops (both on Ethernet), a Wi-Fi laptop, and a Sonos Wi-Fi music system. But, as soon as I turn on the Xperia, it all drops--even from my Ethernet-connected computers. I've reset the router (older D-Link DIR-625) and the DSP modem countless times. The connection comes back temporarily, then dies again. It's EXTREMELY frustrating.

About the only way I can keep the Xperia online for more than a few minutes is to shut every other computer off. HELP!

 

[B. Diddy]

Welcome to Android Central! How many IP addresses does your router's DHCP range include? If the range is set to include only the number of devices you currently have, then connecting another device might cause instability, because it would either cause an address conflict or kick a device off the network. Make sure the DHCP range is wide (like 192.168.0.1 to 192.168.0.255).