How to set up DIGI WR21 abnd WR31 to unlock after outages.

I’m having issues with WR21 and WR31 Digi Modems outfitted with ATT SIMs locking up. They are running FW: Sometimes a 30-second power cycle fixes the issue. When the 30-second power cycle won’t fix the lockup, a reload or upgrade to the newer firmware will. I’ve noticed this issue happening a lot more frequently after the 3G to 4G shift with ATT. My WR21 and WR31 modems with Verizon SIMs installed don’t have these issues.