I’m creating this post in hopes others with my issue can come across it and find a faster resolution than I did.
Current Devices: Raspberry Pi 2, 3B+, 02W, 4B+ and 5. using SixFab 3G/4G<E Base HAT Quectel with the Quectel EC25-A and an AT&T Prepaid SIM.
These devices worked flawlessly together in the past. I work on my project every so often when i have a week or more off of work, usually around Christmas time. In December 2023 i decided to start my project back up again, went to the AT&T store, got a prepaid sim, but now it wouldn’t work. i could send and receive SMS messages, i could connect to the cellular data network and obtain an IP address, but cold not transmit data. I followed the AT&T 3G Sunset Guide thinking this was an issue, even though the EC25A is capable of 4G/LTE, but the command
AT+QCFG=“servicedomain”,1,1
always resulted in ERROR.
Long story short after countless Raspberry Pi’s, AT configurations, troubleshooting, contacting SixFab support multiple times, Driver and OS reinstalls, QMI, PPP and ECM connections, the problem is with AT&T. I went to T-Mobile store, got a $10 prepaid sim, and voila, send and receive text still, but now able to transmit and receive data over the wwan0 interface.
Hope this helps someone in the future.