Skip to main content
icystr123
icystr123
New Member
May 26, 2020
Question

IP address conflict when setting up FortiGate 60E

  • May 26, 2020
  • 1 reply
  • 13419 views

I have a new FortiGate 60E that I have connected in this way:

ISP 1 WAN -> WAN1

ISP 2 WAN -> WAN2

Port 1 -> external network switch to LAN

 

I'm not getting any network connectivity to the external switch from the FortiGate 60E.

 

Whenever I log into 192.168.1.99 it gives me a notification that says "The IP address of interface "internal" conflicts with the DHCP address received by interface "wan1""

 

The IP address of "internal" is 192.168.1.99/255.255.255.0

The IP address of "wan1" is 192.168.1.110/255.255.255.0

 

I've tried changing the IP address of "internal" to 192.168.2.99 and also 192.169.1.99. I've also tried changing the IP addressing mode to "DHCP" and also "Dedicated to Fortiswitch" but it seems no matter what I do the FortiGate immediately gets disconnected when I submit the change and I can't log into it again unless I perform a factory reset. Am I doing something wrong here?

    1 reply

    Toshi_Esumi
    SuperUser
    Toshi_Esumi
    SuperUser
    May 27, 2020

    If you can't change the subnet with ISP's router (I think you can if it's a decent modem/router), you need to change your internal interface to something else other than 192.168.1.99/24. When you change it, like 192.168.2.99/24 you need to change DHCP server config on the internal interface to reflect the change on the interface. Otherwise, the devices you hook up on the LAN couldn't get a proper ip within the new range.

    icystr123
    icystr123Author
    New Member
    May 27, 2020

    Thanks for your reply. I managed to change my ISP router IP address to 192.168.3.1 which also changed the subnet of everything attached to the ISP router to 192.168.3.X. As a result I now can't log into the fortigate at all. I'm guessing its because the subnet should be 192.168.1.X? I've tried factory resetting multiple times but I haven't been able to get back in

    Toshi_Esumi
    SuperUser
    Toshi_Esumi
    SuperUser
    May 28, 2020

    You're not coming from Internet side (via ISP router) to get in the FGT, are you? Then your local login interface is still internal. There is no reason to lose connectivity. Regardless I recommend using the console access (CLI) when you change the local interface config on the FGT.

    Terms & ConditionsAccessibility statement