Board Thread:Game Discussion/@comment-110.54.215.9-20180104055025/@comment-209.116.248.18-20180131195503

I use the same phone but am reluctant to update to 11.2.5 IOS, because it fixes that security bug that every processor in the world is vulnerable to. If you updated, even to not this version- kindly reset your network settings by going into >Settings >General >Reset, then ONLY select Reset Network Settings (your phone will automatically reboot).

Re-authenticate to your router and see if it works better.