HandleTunnelDisconnected disconnection reason: 13 Failed Unknown

Question

Hi, i have installed FortiClient 7.4.3.4726, and configure vpn to connect in customer vpn, but the connection don’t works, i have bellow error:

[2026-05-27 12:01:21.6932022 UTC-03:00] [12040:11004] [FortiVPN 2041 error] fortivpn::StateMachine::HandleTunnelConnectFailed session 1's (.\josan) vpn connection failed (reason: "Failed Unknown")
[2026-05-27 12:01:21.6958494 UTC-03:00] [12040:11004] [FortiVPN 2370 info] fortivpn::StateMachine::HandleTunnelDisconnected "Agrex do Brasil LTDA" is disconnected.
[2026-05-27 12:01:21.6968655 UTC-03:00] [12040:11004] [FortiVPN 2406 info] fortivpn::StateMachine::HandleTunnelDisconnected disconnection reason: 13, ("Failed Unknown")
[2026-05-27 12:01:21.6968739 UTC-03:00] [12040:11004] [FortiVPN 2432 error] !!! fortivpn::StateMachine::HandleTunnelDisconnected session 1 (.\josan) "Agrex do Brasil LTDA" disconnected unexpectedly!
[2026-05-27 12:01:21.6973074 UTC-03:00] [12040:11004] [FortiVPN 2446 info] fortivpn::StateMachine::HandleTunnelDisconnected Notifying gui this was a connection error

Anyone can help me?

Sheikh · Answer

Hello ​@JASN,Generally “disconnection reason: 13 (Failed Unknown) in FCT usually means the VPN negotiation vailed before authentication completed and mainly revolves around following.- TLS/Cipher mismatch- EMS server compliance or restrictions (if in place)- Invalid VPN settings.- Certificate validation/SNI issuesHave you checked the compatibility of FCT with FortiGate firmware versions?What is the TLS version enabled/configured in FortiGate? Try to use TLS 1.2You can also try to use another network or hotspot. There might be some restrictions or policies causes this.regards,Sheikh

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