Hi, community Forti. I have a fortigate 100D but a WAN port broke down; now ot only gives me 10 mbps instead of the normal speed. So I want to use a LAN port as a WAN port but a I have some questions.The Lan port can fuction properly? The speed is 100 mbps The Wan port can be repaired?I know that I need change policies and more things. All for the LAN port.

New Member

Question

Use LAN port as a WAN Port

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Hi, community Forti.

I have a fortigate 100D but a WAN port broke down; now ot only gives me 10 mbps instead of the normal speed. So I want to use a LAN port as a WAN port but a I have some questions.

The Lan port can fuction properly? The speed is 100 mbps
The Wan port can be repaired?

I know that I need change policies and more things. All for the LAN port.

farhanahmed

Staff

LAN port should function properly.

For the WAN port - I am sure you have tried changing the speed - but does the nic (get hardware nic <interface-name>) show 100mbps or 10?

www.farhan.ch

Charly3312Author

New Member

The Wan port show a speed of 100 mbps, I thought the newtwork cables was damanged so I change the cable but the result was the same.

All that’s left is to test it on the other WAN port I’m using.

osoleimani

Staff

Hi Charly3312,

Since the interface reports a 100 Mbps link and replacing the cable did not change the behavior, testing the other WAN port is a reasonable next step, provided it can be tested safely without disrupting your connection.

If the performance issue persists on the original port but not on the other one under comparable conditions, that would help narrow down whether the issue is specific to the port or its configuration.

I hope the test helps clarify the cause.

Charly3312Author

New Member

But in any case, I can use a LAN port as a WAN port, and it should work without any issues. Right?

osoleimani

Staff

Hi Charly3312,

You can generally repurpose an available physical LAN port as a WAN interface on the FortiGate 100D.

If the port is part of the integrated hardware switch, you may need to remove it from the switch configuration before configuring it independently. You would also need to review the interface IP settings, routing, firewall policies, and NAT configuration to ensure traffic uses the new WAN interface correctly.

So, the port can serve as a replacement, provided it is suitable for the required connection and the configuration is adjusted accordingly.

I hope this helps clarify the option and the configuration considerations involved.

osoleimani

Staff

One additional point to check is the speed and duplex configuration on both ends of the Ethernet link, including the ISP modem or other device connected to the WAN port.

The settings should be compatible. If the FortiGate interface is configured for auto-negotiation, the connected device should generally also use auto-negotiation. If either side is manually configured, verify that both sides use compatible settings.

After changing the settings, the interface may need to be restarted or the connected device rebooted for the changes to take effect, depending on the device.

I hope this additional check helps.

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