Q: Any fix for the iPhone 6 "incorrect password" WIFI error?

Began shortly after iOS 9 update. We have several customers experiencing the same issue with iPhones and iPads.

Yes, we have been meticulously entering the correct password. We are aware it is case sensitive.

Apparently, this is a some sort of strange intermittent issue. My kid's MX5X2LL/A iPhone 6 will connect to WIFI for a week or two, then completely "forget" the passwords to every single wireless network it ever connected to with no notification or no warning. Then, a week or two later, miraculously connect to WIFI once again. This bizarre bug is driving us bananas - especially with all the data overages. It all seemed to begin upon upgrading to iOS 9. Here's what we've done since September:

• upgraded to iOS 9.1 and subsequent 9.1 updates

• re-upgraded to iOS 9.3.1

• erased and reset network settings at least 12 times

• erased and reset entire phone three times

• reset all wireless routers, changed SSIDs, changed passwords

A few things that did seem to give us at least some sort of progress, yet still unacceptable:

• disabled find my iphone - connected to WIFI immediately, then lost it again about a week later

• connected to Bright House public WIFI hotspot, although not through typical WIFI interface

• connected to two 5G wireless networks, even though it would not connect to the same network's 2G with same or different passwords

Signal strength is great everywhere. I've checked all the obvious and not so obvious stuff. Running a hotspot with no password is dangerous and not an option. It's not thermal, because this happens from a cold start. The only thing I can come up with is a firmware discrepancy in authentication in the WIFI chip used on MX5X2LL/A. Vendors are swapped mid-model in all cell phones, computers, and tablets, and it's usually transparent, so there may be a vendor-specific problem Apple is not aware of.

Apple support has been unhelpful and unfortunately pompous as usual, repeatedly declining there is a problem, and requesting that I send my phone in for a paid out-of-warranty service or replacement, which is NOT a solution, thanks. There are at least hundreds if not thousands of people posting here who have the SAME EXACT PROBLEM. My last post was deleted because some Apple genius somehow surmised there was funny business going on, but I can assure you and prove it has NOT EVER been hacked, cracked, unlocked, or jailbroken, whatever that means. Perhaps they have a mandate to delete posts that indicate their hardware may not "just work."

<Edited by Host>