I have had the same problem and had updated the Winegard system software and modem firmware to the latest versions. From this, I was able to connect to Verizon, however, I have been experiencing disconnects from the Verizon network and getting "Denied Access" on the Winegard. After spending 8 hours of phone calls into tier 2 network support at Verizon, it appears that the Winegard device is not being fully activated on the Verizon network - it shows a "pending create" state to Verizon when the Winegard is showing "Connected" on my end. This issue results in daily disconnects and inconsistent connectivity I have power cycled the Winegard device countless times. Verizon states they have no support details on the Winegard device so cannot diagnose the problem - they simply cannot see it connecting to the network and therefore we have to raise a ticket with Winegard directly.
So, I think Winegard stating that this device supports the Verizon network is way over stated.
I will continue to pursue this and see if I can get a call back from Winegard support to resolve the issue with a patch or the like.