L2TP over IPSec VPN tunnel not connected, if the NSG is located behind the NAT gateway.

Zyxel_Chris Posts: 608
Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate 50 Answers 500 Comments
 Zyxel Employee
edited July 2022 in Nebula Security Gateway
  1. In this scenario you will need to configure the port forwarding on NAT gateway (NSG's uplink device) in UDP port 500 4500 and 1701.
  2. If your client is using Windows 10 then since in default setting it won't support this scenario (VPN server behind the NAT) then need to modify the registry. Refer to Windows knowledge base or here, please reboot the computer after the setting.
  3. Also note the Windows L2TP security tab setting because NSG not support EAP MS-CHAPv2 therefore please use MS-CHAPv2