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

26 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.

  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!

    • I have been trying to connect with FortiClient from home but the connection always stops at 45 and gives me the error: “The server you want to connect requests identification, please choose a certificate and try again. (-8)” The problem is, when I ask the people in charge of the server, they say I shouldn’t need a certificate and it is the first time they see this error. I followed their instructions exactly and it always gives me this error. Could there be something wrong with my setting? I am running Windows 7 32-bit.

      PS If you are more comfortable answering in french, I am also french.

    • Thank you, I had unchecked the “do not warn about certificate” and so Forticlient was stopping at 40%. After I checked the box, Forticlient connected successfully.

  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

  7. Does anyone have the FortiClient SSL VPN working on Windows 8? My fortissl network device in control panel has a status of ‘Unavailable – device missing’ instead of PPPoP WAN Adapter and I can’t find any way to fix it. Connection process stops at 98%

  8. I have the same problem. Connection stops at 98% and will not connect. when I check fortissl network it states this connection is not available becasue there is a problem with your modem or network adapter? Is there anyway I can fix this. i have uninstalled and reinstalled and still has not resolved the issue

  9. for 40% stop of forticlient it was proxy setting issue in IE if uncheck it.. for 98% stop it was windows service issue… windows event log service was off.. i started it and able to connect to ssl-vpn.

  10. I neither have a VNC nor TeamViewer but still I’m getting this issue on my windows8. When I tried pinging to my server. I’m getting the following:

    Pinging with 32 bytes of data:
    Reply from bytes=32 time=11ms TTL=246
    Reply from bytes=32 time=27ms TTL=246
    Reply from bytes=32 time=53ms TTL=246
    Reply from bytes=32 time=96ms TTL=246

    Ping statistics for
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 11ms, Maximum = 96ms, Average = 46ms

    Please help me to get rid of the issue.

  11. Had also VPN unreachable at 40% (-5), it was due to the fact that in IE advanced settings we disabled SSL 2.0,SSL 3.0 and TLS 1.0 but tls 1.0 is used for the SSL connection to work. Checked this “on” again solved the problem.

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