Clavister for android fails to connect to ocserv

Description of problem:

There is a company named: Clavister which has three applications

Clavister OneConnect for iOS
Clavister OneConnect for Android
Clavister OneConnect for Windows

and based on this link Clavister (Classic) SSL VPN vs OneConnect (OpenConnect based) SSL VPN it seems to be some compatibility between these two.
So I tested the iOS client and could connect to ocserv, but for Android , the client gave this error:

authentication failed

and for Windows gave:

failed to connect no content-length header

Version of ocserv used:

ocserv --version
ocserv 1.1.6

Compiled with: seccomp, radius, gssapi, PAM, PKCS#11, AnyConnect
GnuTLS version: 3.6.13

Client used:

Latest versions of:

Clavister OneConnect for iOS [ connected ]
Clavister OneConnect for Android [ failed ]
Clavister OneConnect for Windows [ failed ]

Distributor of ocserv

cat /etc/os-*
NAME="Ubuntu"
VERSION="20.04.5 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.5 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal

How reproducible:

Describe the steps to reproduce the issue:

install the clients are try it

Actual results:

Based on ocserv log, it seems the a session is created , but immediately closes

Dec 29 19:35:58 localhost ocserv[40060]: note: skipping 'pid-file' config option
Dec 29 19:35:58 localhost ocserv[40060]: note: vhost:default: setting 'plain' as primary authentication method
Dec 29 19:35:58 localhost ocserv[40060]: note: setting 'file' as supplemental config option
Dec 29 19:35:58 localhost ocserv[37906]: sec-mod: sec-mod instance 0 issue cookie
Dec 29 19:35:58 localhost ocserv[37906]: sec-mod: using 'plain' authentication to authenticate user (session: w9KmIw)
Dec 29 19:35:59 localhost ocserv[37906]: sec-mod: initiating session for user 'wR6IZw' (session: w9KmIw)
Dec 29 19:35:59 localhost ocserv[37906]: sec-mod: temporarily closing session for wR6IZw (session: w9KmIw)

Expected results:

since the ocserv configuration is the same, Android and Windows client could connect to ocserv.

Edited Dec 30, 2022 by Dimitri Papadopoulos Orfanos