1. Restart - the easiest way to fix wifi error on iOS 11
Not only fix the error of not accessing the wifi, restarting the device is also a "panacea" of iPhone or iPad. Do this first when there is an error. If that doesnt work, lets move on to the following ways.
2. Exit and reconnect to the wifi network
On the wifi network you are using, choose to forget the network (Forget This Network) and log in again from the beginning can help you fix the wifi error on iOS 11 .
3. Reset network settings
Open Settings> General> Reset> Reset Network Settings ( Settings> General> Reset> Reset network settings). This will clean the cache and clear the DHCP settings as well as browsing history and other network related information.
4. Disable VPN
You can try disabling the VPN by switching Status from Connected to Not Connected in the settings. In some cases, this also helps return the wifi connection.
5. Set up custom DNS
A problem with your ISPs DNS server can also be the cause of your device being unable to connect to the wifi. In this case, you can switch to Google DNS or OpenDNS. You go to Settings> Wi-Fi> Click on the name of the Wi-Fi you are using> Configure DNS> Check on Manually and proceed to add 2 servers 188.8.131.52 and 184.108.40.206.
6. Use wifi Assist
Wifi Assist is the feature that provides more reliable Internet connections when your wifi network becomes unstable. To turn wifi Assist on / off, go to Settings and navigate to Cellular (Mobile in some regions) and scroll down to the bottom where you will see wifi Assist.
7. Restore and reset the device
If none of the above methods can fix the wifi error on iOS 11 , please perform a factory reset for the device. Remember to back up your data first. In this way, all problematic settings on your iPhone or iPad will be removed, as it will look like a new device.