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Daniyal007
Daniyal007
Explorer
April 28, 2025
Question

Wan link speed issue

  • April 28, 2025
  • 3 replies
  • 1408 views

Hello there,

I have fortigate 201G and i configured 4 wan links on fortigate.

4 wan links are added in virtual wan link and configured the sdwan rule as IP based.

Now i have no traffic shaping is enabled in my fortigate but i am facing issue regarding link speed as download speed is to much slow like one Mb and upload is 90 Mb, i have 100 Mb links.

 

Manual static routes are also configured in FortiGate no route is configured with virtual wan link all four default routes are configured with the their respective interface.

 

Kindly help! i have checked everything there is no traffic shaping, no MTU mismatch, every policy is well configured with the outgoing as virtual wan link and incoming as my lan i cant find anything which restrict the traffic for outgoing

3 replies

Stephen_G
Moderator
Stephen_G
Moderator
May 2, 2025

Hello,

 

Thank you for using the Community Forum. I will seek to get you an answer or help. We will reply to this thread with an update as soon as possible.

 

If anyone viewing this topic has any knowledge on this, I encourage you to reply.

 

Thanks,

Stephen_G - Fortinet Community Team
Stephen_G
Moderator
Stephen_G
Moderator
May 6, 2025

Hello,

 

We are still looking for an answer to your question.

 

We will come back to you ASAP.

Once more, if anyone has any advice, please share!

 

Thanks,

Stephen_G - Fortinet Community Team
Stephen_G
Moderator
Stephen_G
Moderator
May 6, 2025

Try the steps in this article to see if they help: https://community.fortinet.com/t5/FortiGate/Technical-Tip-Low-throughput-troubleshooting/ta-p/272657

Stephen_G - Fortinet Community Team
Daniyal007
Daniyal007Author
Explorer
May 14, 2025

Hello Stephen,

Thanks for you response.

I found out that the issue is with the Sdwan rule and preformance SLA.

i checked my internet links with out sdwan configuration just (incoming lan interface towards wan internet interface) and it working fine .

when i add my four wan links in sdwan zone then and configure performance sla then i got packet loss and speed issues. Here is my sdwan configuration

1-sdwan zone contain 4 Isp.

2-static route 0.0.0.0/0 sdwan interface

3-preformance sla is:

    latency 70%

    packet loss 10%

    jitters 20%

    check interval is 500 ms

4- sdwan wan rule is that i added some important subnets on 2 isps and then added my least       prioritize subnets in other rule with remaining 2 isp

when ever my SLA shows sudden high packet loss then it also cause packet loss in LAN, However i tested the it with out sla and configured the sdwan rule with spill over then it works fine.

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