S4 won't send or receive MMS if Wi-Fi is turned on since 4.4.4 update
My Galaxy S4 has stopped receiving MMS when Wi-Fi is turned on.
Yes, I am aware that Mobile Data must be turned on to receive MMS even over Wi-Fi. However, the only way this phone will send or receive MMS now is if Wi-Fi is turned OFF, which means MMS now runs my data plan usage up, which it is not supposed to do when connected to Wi-Fi. I have a very strong Wi-Fi signal here at home, so please, no replies asking if I have a good enough Wi-Fi signal to receive MMS. It all worked fine until the 4.4.4 update, at which point it stopped working. I am a Uverse customer also, so my ISP and Wi-Fi/Router provider is also AT&T.
I spent hours in chat with ATT Wireless Tech Support yesterday, the end result being that they acted as though, despite the thousands of posts about this exact issue online, this was a brand new issue, unique to me, and they have no idea why this is happening. Their only suggestion was for me to do a factory reset, which of course blows up all my downloaded apps, widgets, phone settings, etc. etc. even though I can back up my pics and other personal files. So Factory Reset is not a satisfactory option for me, especially considering that it is just a "shot in the dark" non-solution that Tech just hopes might help. "Factory Reset" is like "Reinstall Wiindows:" it means the people suggesting it have no clue what is happening and have nothing effective to suggest, so just starting over might work. Or not. Just a way to make me go away, and no skin off their nose because it's not their apps/widgets/settings being blown up.
Can someone please suggest a competent, knowledgeable source of troubleshooting steps and actual solutions to this issue other than the world famous "reinstall Windows" shot-in-the-dark nuclear option? Thanks.