Arlo Go Cameras not working

Our company has 3 Arlo Go Cameras.  They all worked until last month when the 3G phase out started.  I spoke to Arlo and they said they know this is an issue with the AT&T network.  I called AT&T and walked through the trouble shooting steps (resetting camera, taking battery out, reinstalling, software update, etc.) again and again.  Then they sent replacement SIMS.  Still having the same issues.  They refreshed the signal to the SIM, works for couple minutes then goes offline.  So is there any other fixes for this?  Thank you so much for any assistance that may be provided.