MMS over wifi is carrier dependent. Call you carrier and see if they support it. If they do ask them to make sure your account is provisioned for that feature. If after that it is still not working, try Settings->General Management->Reset->Reset Network Settings.
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Bill --- Galaxy Fold 6 512g(VZW), Galaxy Book (original, VZW), Tab S8 Ultra, Tab S4, Galaxy Watch7Ultra(VZW),Galaxy Watch6Classic 47mm(VZW), M8 Smart Monitor, NEO 55" QN90D TV, Buds Pro
I just spoke with someone at Verizon on this and they do not support MMS over WiFi. This is disappointing because I have poor service at my home and it takes 10+ minutes to send an MMS message. Sad that it is 2022 and this is still not available. Why can I call and text via WiFi, but not send an MMS message? Makes no sense.
I have an unlocked S21 and MMS works over wifi. It works with data off and data on and wifi set to the preferred network also. I am also on Verizon, so I think that confirms it works both locked/unlocked on verizion. You do need to have Wifi Calling turn on under connection settings though. That is not a default setting.
