I just upgraded my AT&T Nokia 520 to Windows 8.1 Last Night.
Until then my MMS worked great. Now it won't work at all. I tried sending one to myself because i know that sometimes that helps.
Here are my settings. Please help it is frustrating.
APN: att.mvno
WAP Gateway (URL): 66.209.11.33
WAP gateway port: 80
MMSC (URL): http://mmsc.cingular.com/
MMSC Port: 80
Thanks