I maintain roughly 450 WR31’s for the State of California, recently Verizon did an M2M migration and 10 units failed to reconnect afterward.
Verizon also claimed the Digi WR31 was the issue, however I quickly pointed out to Verizon that the 10 units that failed worked with another Verizon SIM on same APN.
Seems Verizon would rather blame the equipment than themselves as standard operating procedure!
Turns out after pointing out that the replacement SIMS worked as expected, but the old SIMS only attached to GPRS and not the data or assigned IP that Verizon screwed up the provisioning after their M2M migration.