Delayed group texts?!

[AC Question]

I have a Note 4, on AT&T, and up until tonight I haven't had any problems with group messages. A few hours ago i noticed that my friends weren't responding to my posts in the group and I realized that I was receiving their texts from almost an hour before so i wasn't ever in the conversation to begin with. We started a new group message but i am still not seeing their messages until 15 minutes after. I don't know if my friends' phones/ networks have anything to do with it or not, two of them have iphones on at&t and the others have an iphone and another note 4 on T-Mobile. This is driving me insane and I wish i could find a solution, please help.