I have an Actiontec MI424WR Rev. I wireless router. All firmware has been upgraded on the router. I am unable to send or receive pictures (MMS) over WIFI from my iPad, iPhone or Samsung Galaxy S4. The Apple devices have been updated to iOS 7.0.4 and the S4 was recently updated to Android 4.3. I can send and receive text messages (SMS) from these devices over WIFI. And, of course, I can send and receive both SMS and MMS messages over cellular 3G and 4G networks from the iPhone and S4. I attempted to port forward certain ports on the router specifice for iMessage (per an Apple forum) for the iPad and iPhone. These include ports 80 (TCP), 443 (TCP) and 5223 (TCP). After powering down the devices and router and rebooting, I was still unable to send or receive MMS over WIFI with those devices. I haven't tried any port forwarding for the S4 but I think it's safe to assume that I will encounter the same issues with that device since it did not work for the Apple devices. BTW, no other problems arise with Facetime, Netflix or other streaming services, only pictures via messaging over WIFI.
Does anyone have any suggestions?