Fixed by simply renaming WIFI network name (Or SSID Name). I tried all of these below. None of these worked for me. Renaming forced other devices to reconnect, but I had no problem reconnecting other devices with new network name as I had only 6 to 8 devices.
My Phone: iPhone 6, iOS 11.2.6
1) Force Restart
2) Wifi Channel change
3) WMM disable
4) Router restart with router being off for 2 mins. Nope.. it didn't work. Tried unplugging power card for both modem and router. That also didn't work.
5) Static IP for my iphone
6) Disabled Wi-Fi Networking
7) Reset Network Settings
8) Forget this Network
9) Removed Share My location devices except current one.
8) Disabled WiFi assist
9) Disabled WPS
10) Enabled IPv6 in Netgear Router
11) Even moved away 5 miles just to make sure different Network gets picked up from LTE and hoped that would flush some WiFi network cache along with LTE cache if any. Realized I didn't have to do this stupid thing of moving away from home as they are not at all related. But, you never know stupid things work some times. 😁
12) Disabled WiFi and Enabled WiFi multiple times.
13) Tried Airplane mode and disabled Airplane mode
14) Tried personal hotspot on another phone to connect from problem phone and see if that would flush cache.. Nope that didn't work either
15) Finally the only thing that worked for me was RENAME THE WiFi Network Name for both 2.4GHZ and 5GHZ.
