I am currently using textra texting but have also tried android and samsung messages. At times i send either a group chat or mms photos and the phone like 20 mins later says unable to send. Ans asks if i want to retry. Even thoufh it says unable to send sometimes irs still senss and then sends it again. And at times if there is alot of texting like a group chat and pucs then forget it, nothing works till it resets. Online many posts say the problem is the phone sofrware and to goto airplane mode for a bit anf back and then it all works again. I have contacted verizon and textra for concern and done some research online forums. I have replaced sim card and also formatted phone to start fresh. So far only thing left is phone software and hardware. And i am going to guess software. Please help.
It's most likely the Verizon MMS service.
I've used Textra with AT&T on Samsung devices for years and never had an issue. Currently we have that setup on S9+, Note 10+, and S20 Ultra with no issues at all.