helpme705 wrote:
Same issue here with iPhone 6, I have a very weak or no WiFi connection since the update to 11.4.1 funny thing my wife has the same phone and hers works fine after the update (at least the WiFi). I put them side by side in my basement and her phone finds two strong signals mine fines none.
Since that is the case, then it would be a good idea to determine if your issue is caused by corrupted data or an app or Setting, or if it is possible a hardware issue. To do this, back up your device to iTunes or iCloud, then erase it. When you see the Hello screen, set it up, but when it asks if you want to do it from a backup, choose to set it up as new.
Once it is set up, if you are not already signed in to your Apple account in Settings, do that.
Then do the basement reception check again to see how the two phones compare.
If the problem is gone, then you know it is related to your data or your apps or Settings, so you would need to manually set up the device. Signing into iCloud would have sync'd your iCloud data, and you can download your purchased media via the iTunes and the App Store.
If the problem is not gone, then you should take it into Apple (in the "clean" that you were testing under), and have them look at the device to see if they can determine the cause of the issue.
How to back up to iCloud or iTunes
Restore from an iCloud or iTunes backup - Apple Support
Best,
GB