Fortigate SSL VPN disconnects between 2-5 minutes suddenly

Dear all, 
Im using fortigate 60E with 5.6 firmware. All users can work only for few minutes & the VPN suddenly gets disconnected. No error comes in. I have installed forticlient 5.6 aas well, but it also give same results

I  have 4M ILL with public IP + 2 other Internet links. load balanced between 3 of them as  ILL(50%)  & 25%  25% .
VPN policy works through ILL

Hey, thanks agent.  I was setting up a new vpn tonight and couldn't figure out the frequent disconnects.  Your listed fix did the trick.
 
Thanks!

Did you try "set route-source-interface enable"?

Hi 
 
Is there any drops in your internet connection  and how many links added for the SSL VPN  .Try to check the logs in the forticlient .
 
Regds,
 
Ashik

HI,
 
Normally if you have More than one Wan link ..Below command will help you to solve disconnection issue .
 
set route-source-interface .
 
Just check if you have already run this command .
 
Regds,
 
Ashik

Hi,
 
Try this 
 

Tunnel-mode connection shuts down after a few seconds

This issue can occur when there are multiple interfaces connected to the Internet (for example, SD-WAN). This can cause the session to become “dirty.” To fix this, you must allow multiple interfaces to connect without issue.
If you are using a FortiOS 6.0.1 or later, use the following CLI command:

config system interface
  edit <name>
    set preserve-session-route enable
  next
end

If you are using a FortiOS 6.0.0 or earlier, use the following CLI command:

config vpn ssl settings
   set route-source-interface enable
end

 Regds,
Ashik