FortiClient 7.4.1 (windows) cannot connect to VPN via Proxy.

[k-saku]

When VPN connection using FortiClient 7.4.1.1736 is performed in an environment via a proxy
The status is stuck at 10% and I get the message "Unable to establish a VPN connection, the VPN server may not be accessible." and
The VPN connection fails.
In 7.4.0, the connection is successful, but is it a bug?
By the way, the macOS version succeeds with 7.4.1.

[Anthony_E]

Hello k-saku,

Thank you for using the Community Forum. I will seek to get you an answer or help. We will reply to this thread with an update as soon as possible.

Thanks,

[HoiFree]

Hello Anthony,

This change happened since Forticlient v7.2.5 & v7.4.1 and caused connection problem with proxy. Will this be handled?

Thanks.

[kaurm]

Hello k-saku,
Please provide the following command output

diag debug reset

diag debug application sslvpn -1

diag debug enable

Please check if TLS 1.1 and TLS 1.2 are enabled on the FortiGate, enable them in Internet Explorer as well.
Thanks

[k-saku]

Thank you for your response.

For command output, see
Please forgive this as it contains information about the customer environment.

However, I did some debugging and nothing was recorded.

(By the way, in the test with a different version, the debug log was recorded. ）

TLS 1.1 and 1.2 are also enabled on both sides.

Best regards.

[k-saku]

Also, when you take a packet capture of the PC side with wireshark
In FortiClient v7.4.0, etc., which can be connected, the remote gateway (Fortigate) was accessed via a proxy, but in v7.4.1, SYN was sent directly to the remote gateway (Fortigate), and communication failed without an ACK being returned.

[TomasM12]

I have the same problem on FortiClient 7.4.3 and cannot connect to VPN via Proxy. On FortiClient 7.4.2 it working OK but I need 7.4.3.

[sferoz]

Hi TomasM12,
Can you help share the FGT config, issue related debugs/sniffer, TAC case if any to sferoz@fortinet.com for more investigation.
Thanks.