So this is truly a head scratcher to me. My mobile provider is Xfinity mobile, who is an mvno of Verizon, and ever sense I upgraded to my Pixel 4A (5G) I have been having issues while trying to send MMS messages, mainly they don't work (fail to send 9 out of 10 times) but if I shut off WiFi and just use mobile data, I have no problems at all sending MMS messages. My providers only solution is to reset network settings on the phone, which is pointless considering I bought the phone from them and only used their service, so resetting the network settings is pointless. But I have diagnosed the issue down to the home WiFi network, it only fails to send when on the home network. I am connected wireless to the 5GHZ WiFi, and even dropping to the 2.4GHZ does not resolve the issue. I am completely confused by this and can not begin to figure out what to look at. I have reset the modem and router a few times just to make sure that is not the issue, but it had not made any difference. The modem and router are both ones that we have purchased and do not belong to Xfinity. Everything else wired and wireless work flawlessly, so I can not fault the ISP in this situation, but it makes me really wonder why.