SSLVPN tunnel connection failed (Error=-20105) after SSL_get Error 5, WSAGetLastError 2746

[iivel]

Some of our users are confronted with this problem pretty randomly while trying to establish a SSLVPN connection. Usually, 2nd or 3rd attempt are working.

The reference tells noting about error -20105 related to connection problems (other than log upload failed, which is disabled).

I could not find anything related to error code 20105 in this forum so far - any suggestions?

A typical log file pattern looks like this:

30.03.2021 15:54:14    Error    VPN    FortiSslvpn: 16144: error: poll_recv_ssl -> SSL_get_error(): 5 30.03.2021 15:54:14    Error    VPN    FortiSslvpn: 16144: error: poll_recv_ssl -> WSAGetLastError():2746 30.03.2021 15:58:05    Error    VPN    id=96603 user=SYSTEM@NT-AUTORITÄT msg="SSLVPN tunnel connection failed (Error=-20105)." remotegw=extranet.xxx.xx vpnstate=connected vpntunnel="SSL VPN" vpntype=ssl vpnuser=xxxxx

FortiClient 6.0.9 on Windows 10 (2004).