try removing the network from within the phones wifi settings. "forget" is the setting on my phone. After that reboot and try connecting back to the wifi after youve reset your internet devices (router, modem, etc.) . If i.p conflict was the culprit this should fix the issue.
If you're still having issues with the connection you could always try logging into your modem and seeing whats connected to your A.P. (for my setup it would be 192.168.1.1 into internet address bar.) Or you can download a network monitoring tool for a more advanced diagnosis and go from there.