Z5 premium wifi problem

[Haarith4lyf]

Hi my z5 premium has some issue with the wifi. Before my phone could hold the wifi connection from my room very well but now it has gone really bad and the wifi disconnects from my phone if i am using snapchat or sometimes it will happen regardless and it comes on and off. Its shows the explanation mark for a few seconds then goes off and wifi is on but the connection is soo bad cant use internet or youtube as it takes ages to load up. Help me really considering changing this phone

[Uliwooly]

How far is the router from your phone? how many walls are in between the router and your phone?

[Haarith4lyf]

The router is one floor from the phone and it isnt tht far because it even loses connection when i get out my house in my garden before it could hold connection from a few houses

[Uliwooly]

Settings > about phone > diagnostics > test > test WiFi 

or 

you can contact your Local support