I've been dealing with this all week from behind firewall. Outside of firewall say, with cellular AP i can connect fine to vpn. I was thinking Windows update broke something in L2TP settings. I've removed adapters and reset network adapters to no avail. Not sure the configuration change is the culprit. I've also removed Windows updates for the past month. My issues seem to be from behind any type of NAT'ed firewall I can't connect to Meraki. Perhaps the same is going on for you. I've opened a ticket with Meraki. NAT-T on/off in registry doesn't seem to make a difference.    ... View more