Troubleshooting Tip: Gateway IP showing as next available IP in VPN client range when connecting to IPsec dial-up tunnel

[rishab444]

Description	This article describes behavior where the gateway for the routes pushed by split tunnel configuration show as the next IP in the IPsec VPN Client Range.
Scope	FortiOS.
Solution	This is expected behavior. By default, the IPsec connection does not push a default gateway to the Virtual Ethernet Adapter on the End User machine unless mode-config and DHCP are being used. Ethernet adapter Ethernet 6: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Fortinet Virtual Ethernet Adapter (NDIS 6.30) Physical Address. . . . . . . . . : 00-09-0F-FE-00-01 DHCP Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes Link-local IPv6 Address . . . . . : fe80::c56d:1f61:4835:5f7e%19(Preferred) IPv4 Address. . . . . . . . . . . : 10.99.91.1(Preferred) Subnet Mask . . . . . . . . . . . : 255.255.255.255 Lease Obtained. . . . . . . . . . : Monday, April 14, 2025 8:15:41 PM Lease Expires . . . . . . . . . . : Friday, May 22, 2161 2:44:51 AM Default Gateway . . . . . . . . . : DHCP Server . . . . . . . . . . . : 10.99.91.2 DHCPv6 IAID . . . . . . . . . . . : 318769423 DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-2A-87-3D-66-00-41-72-74-2E-01 DNS Servers . . . . . . . . . . . : 192.168.113.192 96.45.46.46 NetBIOS over Tcpip. . . . . . . . : Enabled For the routes learned via split tunnel, populating them into the routing table requires a gateway, which uses the DHCP Server IP (the next available IP from the IPSec VPN Client Range) to forward the traffic destined to these networks towards the tunnel. C:\Users\Fortinet>route print =========================================================================== IPv4 Route Table =========================================================================== Active Routes: Network Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 192.168.1.99 192.168.1.125 15 0.0.0.0 0.0.0.0 192.49.9.1 192.49.9.5 15 10.0.0.0 255.0.0.0 10.99.91.2 10.99.91.1 1       <---------- 10.9.16.104 255.255.255.255 192.168.1.99 192.168.1.125 15 10.99.91.2 255.255.255.255 On-link 10.99.91.2 257 127.0.0.0 255.0.0.0 On-link 127.0.0.1 331 127.0.0.1 255.255.255.255 On-link 127.0.0.1 331 127.255.255.255 255.255.255.255 On-link 127.0.0.1 331 192.49.9.0 255.255.255.0 On-link 192.49.9.5 271 192.49.9.5 255.255.255.255 On-link 192.49.9.5 271 192.49.9.255 255.255.255.255 On-link 192.49.9.5 271 192.168.1.0 255.255.255.0 On-link 192.168.1.125 271 192.168.1.125 255.255.255.255 On-link 192.168.1.125 271 192.168.1.255 255.255.255.255 On-link 192.168.1.125 271 192.168.241.1 255.255.255.255 192.49.9.1 192.49.9.5 15 224.0.0.0 240.0.0.0 On-link 127.0.0.1 331 224.0.0.0 240.0.0.0 On-link 10.99.91.2 257 224.0.0.0 240.0.0.0 On-link 192.168.1.125 271 224.0.0.0 240.0.0.0 On-link 192.49.9.5 271 255.255.255.255 255.255.255.255 On-link 127.0.0.1 331 255.255.255.255 255.255.255.255 On-link 10.99.91.2 257 255.255.255.255 255.255.255.255 On-link 192.168.1.125 271 255.255.255.255 255.255.255.255 On-link 192.49.9.5 271 ===========================================================================