Multi-User Collaboration - LAN only? VPN possible?

Yes, they have a hard time with VPN there, I can recommend you one service to find a VPN. When I have problems with such a subnet, I just immediately find a new one. Be sure to check them out if you need a VPN. I think you can definitely find the right one there. I also really like the fact that there is information about both free and paid services. I hope I was able to help you.