Can't send or receive MMS texts

[PapawMike]

Recently ( 4 to 6 weeks) noticed that I am unable to send or receive MMS texts. Don't send many group texts or pictures so it kind of slipped by until I really needed to and couldn't.
Samsung Galaxy J3 phone. Phone was "originally" an ATT phone but I've been using it on the Straight Talk system for almost a year.
OS is Oreo 8.1. Android Security Update on 9/1/18. Oreo 8.1 and Android Security Patch are dated 9/7/18.
Have reset the phone via the method that doesn't wipe my information and that didn't work. So backed everything up and did Factory Reset. Still couldn't send/receive MMS texts. Got with Straight Talk and set up an APN with their settings (instead of the ATT ones that had been working fine) and still unable to Send/Receive MMS text. Got with Samsung and after reviewing steps already taken they recommended to take it to a walk-in service center.
Not an expensive phone but it was working great and now not. Any suggestions appreciated.

 

[B. Diddy]

Welcome to Android Central! Are you connected successfully to mobile data? You're able to browse normally while connected to 3G/4G?

Are these the APN settings you're using? https://bestmvno.com/apn-settings/straight-talk-wireless-apn-settings/

 

[PapawMike]

Straight Talk sent the following via sms which I put in a new APN.

Name: ST APN
MMSC: http://mmsc.mobile.att.net
MMS Port: 80
MMS_APN_TYPE: default,mms,supl

If a setting was not directly mentioned in the text I left it blank except as below.
APN Protocol & APN Roam were left at the ATT setting of IPv4/IPV6.

Using the "new" APN the phone sends/receives sms, phone calls, internet, etc just still no MMS function.

 

[B. Diddy]

Just to be sure, did you try the APN settings in that previous link?

 

[PapawMike]

Not as of yet. Will do as soon as I get to the house.

 

[PapawMike]

Used the Straight Talk AT&T APN on the link you sent and was able to Send/Receive MMS! Even after I restored the phone with backed up Data it worked! Thanks so much for your help! You are a scholar and a gentleman in my book.

 

[B. Diddy]

That's great! Maybe you need to give that info to the Straight Talk support agents.