FortiClient SSL VPN not connecting, status: connecting stops at 40. Unable to establish the VPN connection. The VPN server may be unreachable -5

Today I got a phone call from a client who wasn’t able to connect to his VPN, he was constantly getting Unable to establish the VPN connection. The VPN server may be unreachable error when he tried to connect, while everybody else was connecting without a problem.

His FortiClient status would always stop at 40 when connecting.
There can be several things that can cause this problem, one of them might be an improper TeamViewer upgrade.

Besides TeamVIewer you might also check if you’re using some other VNC based remote access software on the problematic PC, try disabling it or uninstalling to check if it will get your FortiClient working (I had problems with computers that had TeamViewer and Gbridge installed at the same time).

FortiClient unreachable error

Uninstall your old version of TeamViewer when upgrading

If you are upgrading your old version of TeamViewer be sure to uninstall the old one before you install the new version, otherwise you will have both versions installed and problems with your FortiClient.

It seems that besides FortiClient, Windows gadgets also wont work properly if you have two versions of TeamViewer installed. (Specifically, the default weather gadget in Windows 7 wasn’t getting new data because of it)

With this type of error you might also try checking the router side, if the VPN users are able to connect after the reboot of the FortiGate device, you might try to remove some traffic or event logging on the device

14 thoughts on “FortiClient SSL VPN not connecting, status: connecting stops at 40. Unable to establish the VPN connection. The VPN server may be unreachable -5

  1. Pingback: Common FortiClient SSL VPN errors when connecting hangs fixed

  2. we had the same problem “unable to establish…” Stop at 40 (-5) and found out that Internet Explorer was in OFFLINE Status.
    Regards

    • Thanks for help – in my case the reason was exactly you pointed out. After 3hrs of investigations, upgrading SSLClient, browsing register i’ve found Your post and swithed on the IE. Now my SSL Client works!

  3. sorry for my english i’m french.

    Generally when fortigate ssl block at 40% it’s a ssl certificate problem.
    typically if the option “do not warm about certificate validation failure” are not actived the client open a pop-up at 40% for validate certificate.

    For sample , i had already a problem at 40% because a proxy was configured in internet explorer. And the proxy server diden’t work fine with SSL certificate.

    update forticlient ssl with the last version is a good idea too.

    • I have the same problem is abou the certificate but no matter what I do I can’t make the forticlient to prompt to accept the untrusted certificate on windows 8, this will only prompt in windows xp, if any of you know how to do it please help!

  4. I have exactly the same problem.

    “one of them might be an improper TeamViewer upgrade.” – I do not use TeamViewer

    “you might also check if you’re using some other VNC based remote access software on the problematic PC” – I do not use any such software.

    What else could cause such a problem?

    • do you control the FortiGate device, if the problem resolves after you restart the FortiGate then the issue is on the FortiGate device (It can be extensive logging, or it can sometimes be with multiple IP addresses on the WAN interface).
      You can also check your Internet Explorer settings, if you are using any proxy servers, or if you Internet Explorer is in Offline mode

  5. I have a question please,
    I am able to log in to fortinet from my mobile and is there any way to remote my PC using VPN

  6. the solution is easy. if you have a proxy configurated in internet explorer.. you have to uncheck this options in the browser. and ready..
    go back to connect the forticlient

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