the screen shots you are showing for the APN Settings for ATT do not have anyhting Entered for MMS Port and it should say 80.
That is what my APN settings say - and it is what all previous instructions I have seen for ATT APN have said - I don't know if it is absoutley necessary but I would thnk that it might be important -
Just thought I would let you know
My Phone Galaxy S5 G900T
My Rom: Alliance ROM
My Recovery: [klte][CWM Advanced Edition] PhilZ Touch
My Carrier - ATT
: ☆Galaxy Note 3☆HTC ONE☆Galaxy S IV☆Galaxy Note II☆Galaxy S3☆EVO 4g LTE☆Nexus☆Epic 4G☆Treo(W)☆Palm Treo☆(P)