Be aware, there is a known issue where newer versions of the Quantum Gateway firmware that are automatically pusehd out to these devices prevent VPN connections from being established from devices connected via WiFi. At the same time, there is no issue with wired devices establishing VPN connections. Verizon has access to an internal document on the subject that is not available to us consumers.
I first noticed the problem a couple of months ago and called support. After a LONG time waiting while the tech researched the problem and then started emailing with higher level support technicians, I was finally told that it was a known issue and they would have to roll-back the firmware to a known working version. They said that would take up to 24 hours to complete but it was all working again in only 4 hours or so.
Unfortunately, these devices are set to automatically look for, download and install new firmware. My gateway did that early last week and I was once again unable to establish VPN connections from devices connected to via WiFi. And again VPN from wired devices worked just fine. It took another 90 minutes on the phone to convince the tech it was a real problem, that he should look at the notes from a month before and then waiting while he emailed with others. In the end they finally rolled-back the firmware and it's all working again. Trouble is, I don't think they can stop the automatic updates from happening, so this isn't going to be the end of my troubles. Unless, of course, they actually FIX THE FIRMWARE BEFORE THEY PUSH IT OUT TO THEIR CUSTOMERS!!!
If you wire in another wireless AP (with a different SSID) and connect to it instead, the VPN connections of WiFi work just fine. So it's clear that the problem is very specific to the Quantum Gateway's handling of WiFi connections and what it does/doensn't allow those connected devices to do. If you use the same SSID on the second AP the VPN connections still fail. At least they did for me.