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New Contributor

Slow VPN speed

Hello! Please, help me. 

We use FortiGate 200E in our company.

I have difficulty using the VPN. The speed when connecting to VPN is only 1-2 mbps. How can I fix this? The channel at both ends of 50 mbps

2 Solutions
Contributor II



Are you using SSL or IPSEC .? Is it site to site or Remote access ?


Speed is always depending on your internet bandwidth .If the Internet Link is over utilized then there is no much room for VPN traffic .You better focus on bandwidth management .







View solution in original post

New Contributor III

All - this isn't an issue of CIFS or NFS being slow over VPN because of the inherent nature of those protocols.  This is a bug in the Fortinet software, and I'm surprised it's not a bigger deal to more people.  It happens on  IPSEC tunnels as well.

I've spent a week working on this on devices using various 5.6 versions.

I've adjusted every MTU and TCP MSS setting.

I've adjusted NAT traversal to forced.


The 355kb/sec transfer is the clue - how is it possible multiple people are getting the exact same performance from different servers and different circuits and different hardware?   Because it's an inherant firmware bug.

Someone from Fortinet needs to send out a bulletin to explain this in detail and note the correct firmware version that fixes it for everyone.     Honestly can't believe this has gone on for so long.  I have a ticket open but they haven't yet replied.   Frankly not a good reflection on Fortinet.

View solution in original post


I'm having the same issue.


Someone managed to solve?


My issue believe was on the Juniper side. I had the External/public interface open to SSL/SSH for remote troubleshooting but not using firewall filters. CPU usage was causing bandwidth issue.

New Contributor II

I know this is an old thread, but we are seeing more than a 50% drop between a user's native speed versus when on VPN.  Their internet provider speed is 150M, on VPN it's 46M.  We are on a FortiGate 200E running 7.0.9.  The user has FortiClient via EMS, version 7.0.7


Has there ever been a solution?  We migrated from an old Cisco ASA 5512 and AnyConnect, which was way better performance.  This almost makes me want to just go back.

New Contributor

Hallo Zusammen,

das Thema gibt es ja nun schon sehr lange. Wir sind eine Hausverwaltung für Gewerbeeinheiten. Wir teilen unseren Internet-Anschluss mit vielen Firmen. Unser Anschluss hat eine Breite von 1Gbit sync.
Wir nutzen hier eine Fortigate 100F mit der Firmware "v7.2.8 build1639 (Mature)". Der normale Internetdurchsatz ist bei allen in Ordnung. Aber sobald die Firmen von ihren Rechnern aus eine Client-VPN Verbindung in ihre Zentralen aufbauen reduziert sich der Speed auf die 355 KB/s! Gibt es dafür jetzt eine Lösung? Hier greift definitiv die Fortigate ein. Aber wo?


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