Tente isto:
Exemplo de configuração do servidor DHCP
config system dhcp server
edit 3
set dns-service default
set default-gateway 192.168.100.254
set netmask 255.255.255.0
set interface "SCR-REMOTEVPN"
config ip-range
edit 1
set start-ip 192.168.100.100
set end-ip 192.168.100.199
next
end
set timezone-option default
set server-type ipsec
config reserved-address
edit 1
set ip 192.168.100.200
set mac 11:22:33:44:55:66
next
end
next
end
Defina a fase 1 com Mode Config
desativado
config vpn ipsec phase1-interface
edit "SCR-REMOTEVPN"
set type dynamic
set interface "wan1"
set ip-version 4
set ike-version 1
set local-gw 0.0.0.0
set nattraversal enable
set keylife 86400
set authmethod psk
set mode aggressive
set peertype any
set mode-cfg disable
set proposal aes256-sha1 aes256-md5
set add-route enable
set localid ''
set localid-type auto
set negotiate-timeout 30
set fragmentation enable
set dpd enable
set forticlient-enforcement enable
set comments "based on fortinet kb (FD37351)"
set npu-offload enable
set dhgrp 2
set wizard-type custom
set xauthtype auto
set authusrgrp "VPN-group"
set default-gw 0.0.0.0
set default-gw-priority 0
set psksecret ENC
set keepalive 10
set distance 15
set priority 0
set dpd-retrycount 3
set dpd-retryinterval 5
set xauthexpire on-disconnect
next
end
habilite o DHCP sobre IPsec na fase 2 da VPN.
config vpn ipsec phase2-interface
edit "SCR-REMOTEVPN"
set phase1name "SCR-REMOTEVPN"
set comments "based on fortinet kb (FD37351)"
set dhcp-ipsec enable
next
end