Latest update unstable

Im using Sony Z Ultra, and there is an update for the version. Upon updating it, it seems that my phone refuses to boot up. Please advice

Unstable WiFi (err_name_not_resolved)

I have the newest fw for my S5 and I have a lot of problems with WiFi. Sometimes I just get the err_name_not_resolved
In chrome and then I have to disable and enable WiFi and everything is OK again for perhaps an hour or a day... My phone also keeps getting warm and I suspect it has something to do with WiFi?!

I have tried reinstall my phone and my router is a Asus new one.

Please help. I had problems with WiFi since galaxy s3... (On different routers)

Xperia Dual D6633 WiFi unstable / crashing

Hi,

I have a D6633, a couple of months back Sony released the Lollipop however after upgrading the WiFi keeps on disconnecting randomly; I went to the Sony Service Center however they said there is no problem; I did a repair many times using the PC Companion; however the WiFi just keeps on connecting / disconnecting.

Does anyone have the same problems?