A while back I posted regarding some issues we had with connecting our VPN client using a Verizon MiFi device. The setup involves Mikrotik routers at our offices, and we use the Shrew Soft VPN client. The setup works flawlessly on numerous networks and devices for multiple users. However, when my boss travels he uses his Verzon Mifi to connect from anywhere to check e-mail and such. After working with numerous people in verizon including some higher level techs, we were unable to come up with a solution as to why the VPN could not connect when using their device. We also tried it on literally every mobile hotspot device they offered, therefore leading us to believe the issue was to do with their network infrastructure.
So here's my problem, temporarily i had my boss set up using LogMeIn and it worked great, but he hates it (screen area too small in web browser, etc...). I've tried AT&T's Mifi devices and it goes the same way, the VPN tunnel never fully connects. Basically i'm out of ideas and need a solution that will work with our routers. Any ideas?
TL;DR: I need a VPN solution that works over Verizon Mifi devices and is compatible with Mikrotik routers.