Issue: Unable to establish the VPN connection. The VPN server may be unreachable (-5).

[Premkanth]

Hi,

I am facing an issue with Fortinet Client VPN connection from a particular system.

Issue: Unable to establish the VPN connection. The VPN server may be unreachable (-5).This message is showing always in the time of 40 % of connection

We are using the FortiGate 90D firewall. FortiClient firmware is  5.4.1

Following methods are tried for solve the issue

Method 1

Found 2 way of solutions for solve the issue

[ul]

Change MTU interface using the command prompt

Change MTU interface using the registry change[/ul]

Attaching the link

http://tipsnetworking.blogspot.qa/2015/05/forticlient-vpn-ssl-stops-at-40_27.html

[ul]

Already tried by disabling the AV/Malware products[/ul]

But the issue was not resolve by this changes.

Can somebody help me to solve the issue?

[dphills]

I am having the same issue.  We have figured out that if we go into our internet options and click on the advance tab to reset the browser, we can then login via the FortiClient.  However, we have to do this quite often.  Does anyone know why the FortiClient is tied into Internet Explorer and how it can be bypassed?

[MasterBratac]

For me it was a TLS version mismatch on Fortigate and IE settings.

Check this link:

http://www.layer8.one/for...-may-be-unreachable-5/