Sudden wifi issues

[nori_nori]

I have recently began to have major issues with my wifi connection. The wifi is connected to the phone, but I'm not getting any notifications. The web browsers work fine, and I can stream stuff, the wifi work great when the phone is in use. I find when I open, say whatsapp, messages suddenly appear from hours earlier. The only time this is slightly different, is If I open my emails, and check for new emails, by syncing, nothing happens unless I turn off the wifi, and turn it on again, on the phone. If I'm using whatsappweb, the phone will disconnect after a while, even tho it's on and right next to me. The wifi power saving mode is disabled... Also 'keep wifi on during sleep' is on always. I've not altered a single thing on my router, nor my phone. It's just suddenly started doing this. Can anyone help?

 

[B. Diddy]

Go to Settings>Data Usage. Is Restrict Background Data turned on, either universally, or for any of those individual apps?

 

[nori_nori]

Sorry for the late reply, thanks for getting back to me. The background data is not restricted, either universally or individually. Still the same issue. I've noticed my phone is getting slower, and the battery is draining rapidly... I used to be able to get a good 12hrs out of it, I'm lucky if I can get 5hrs now.