wifi problems

[FaBle]

Hey,

I have the problem that the wifi works on my Xperia z2 only very limited. If my smartphone is connected to the wifi, everything is either very fast and good, or it loads only very slowly and almost did not go. It also disturbs other devices (PC, Playstation, etc.), which are then work very slowly. When i turn of my wifi from the smartphone, all other devices functioning again as always, and everything loads very fast again. I have that problem since one week.
Does anyone have the same problem or can anyone help with?
Thank you

(Sorry for my bad english)

[Uliwooly]

1. are you auto updating the apps when on wifi?

2. do you have auto backup enabled on (G+) while on wifi? 

[Curnow1]

Boot your phone in safe mode. Maybe there's an app which uses alot of internet. You can also try restarting your router. You can try tuning off/on the Wi-Fi optimization in advanced settings. 

[FaBle · Accepted solution]

got it solved. have my smartphone formatted and now it works again.

But thank you.

[BeadyEye]

What do you mean you formatted your phone?