Question about Arris NVG558HX Verizon

We have a customer who has this unit. We are noticing problems with this LTE Router Internet Gateway.  We have multiple devices that will randomly not be able to communicate with our AWS servers. No matter what we do the only thing that can get the units back online and communicating is Resetting the NVG558HX to Factory defaults. It appears it is blacklisting these devices, however, there is nowhere in the router settings that shows our devices are blocked. they show that they are connected. I really need to speak to a tier2 or 3 agent if possible.