take that battery saving or monitoring stuff off your phone ... caused nothing but problems for me... some apps would should down stuff the app claimed was draining battery and then i could only re-open the app that got shut down if i re-booted the phone.
Try deleting the saved network. Do a hard reboot ... keep battery out for 3-5 minutes. Then log back into the network.
Or, problem could be the router. Sometimes at home I have to re-boot my home router .. not always the phone's fault. Hope these tips work.