Follow The Steps -:
1) Simply Disconnect The Wifi And Reboot Your Phone (Sometimes This Work)
2) If Not Work Connect The Wifi
3) Long Press On Connected Network
4) Click "Modify Setting" and Tick On "advance Setting"
5) Copy And Paste From Below With Current Line -:
IP Address: 192.168.1.128
Gateway: 192.168.1.1
Network Prefix Length: 24
DNS 1: 8.8.8.8
DNS 2: 8.8.4.4
6) Done! problem Fix Now