Many years ago I wrote numerous blog articles relating to VPNs, and primarily PPTP VPNs. Hits on those blog pages are up 300% since the Coronavirus outbreak due to people looking for ways to work from home. I wanted to warn PPTP is an old solution and is considered to be “broken” and very insecure. Please consider other options.
Rather than creating new articles explaining how to configure various remote access methods I thought I would provide some suggestions and links as it has all been written before by very talented IT folk.
Firstly VPNs. I would always recommend using a VPN appliance/router over the server itself. It is more secure, authenticates at the network perimeter not the server itself, and allows more control. Cisco, Sonicwall, Juniper, Watchguard, and others provide very good solutions . However one concern with any VPN solution is the fact that though it is a secure tunnel, it also allows any and all traffic between an unmanaged remote client computer and the corporate network. Viruses can travers the VPN tunnel, should the client PC be hacked the hacker has direct access to the corporate network, and the remote user can easily copy/steal corporate data that they maybe should not. In addition VPNs occasionally just do not work due to network addressing, slow ISP service, or blocked protocols by ISPs.
If you do want to set up a VPN on a windows server, I would recommend SSTP. Thomas Maurer has a great configuration guide:https://www.thomasmaurer.ch/2016/10/how-to-install-vpn-on-windows-server-2016/
Perhaps a better option than a VPN is a terminal server, now called a remote desktop server (RD Server). I have never seen the RDP protocol blocked, performance is usually better than a VPN, and all data stays on the corporate network. If set up correctly it uses the Remote Desktop Gateway service and SSL which is very secure. You can, if you like, also use this within your VPN tunnel and if using a business class VPN solution restrict traffic to RDP.
Another alternative if you don’t want to set up an RD Server is to configure the RD Gateway service on your server and allow users to connect securely to their own desktops PCs with the same level of performance. This was a built in feature of SBS and Server Essentials 2016 and earlier. Mariette Knap has a excellent article on configuring the RD Gateway service, specifically on Server 2019 Std:https://www.server-essentials.com/support/setup-rds-gateway-as-a-replacement-for-access-anywhere-from-the-essentials-experience-role
Regardless of what method you use, as soon as you allow any remote access, make sure you configure Group Policy to enforce strong passwords and to lock accounts after ‘X’ wrong password guesses. (I use 5, and lock out for 30 minutes). You can set this on the server for domain wide deployment or on an individual PC using GPedit.msc. For both it is located under Computer Configuration |Windows Settings | Security Settings | Account Policies .
The other alternative of course is to use cloud based services such as Microsoft’s Office 365 which you can from any where, at any time. If dong so, make sure you enable multi-factor authentication for security.
I hope this is of some help and please stay safe n these uncertain times.