My Surf SOHO currently has a USB WAN connection through a Novatel 6620L on Verizon. I am trying to set up the built in PPTP server but am not having any luck connecting. I have tried setting DMZ for the SOHO on the Mifi, and also specifically forwarded port 1723 to the SOHO through the Mifi also with no luck. Is there a trick to making the PPTP work through the Mifi or is that not possible?
It won’t work unless you pay Verizon a one-time payment of $500 for a static IP address that bypasses their 4G LTE NAT. Verizon’s 4G LTE network uses NAT – your Novatel does not receive a public-facing IP address – and there’s no way to get through it, unless you set up an elaborate SSH reverse tunnel, involving a VPS or other publicly accessible server that you can use for a relay.
See here for more info: https://b3n.org/port-forwarding-verizon-wireless-nat/