MMS Still Not Working

I've made multiple attempts to contact Xfinity to resolve an issue of not being able to send/receive MMS messages (i.e., group messages, pictures, etc.) when wifi is turned on. I can only send/receive MMS using the mobile network & when wifi is turned off. This has been affecting all 4 phones on my account for months. I was able to chat with an Xfinity representative twice but now I keep getting the Xfinity game where I answer questions over & over but never get connected to a representative to chat. I was told by the Xfinity rep that my complaint is an Android/Samsung/Google messages issue but every Android/Samsung owner I know who has service through a different carrier is NOT encountering this same issue. I have reset the mobile network, wifi & Bluetooth settings multiple times on our phones, yet still the issue remains. Our family now uses up all of our data because we have to keep wifi turned off. Xfinity really needs to fix this. I've read this same complaint multiple times from Xfinity customers as far back as 2021.