After upgrading my docker and os, LDAP->ldap_server always lost its data.

[semaphor34]

Description:
OS: Ubuntu Server 20.04 lts
Docker
After upgrading patching my os and docker , the protected member ldap_server of class LDAP always looses its data.
The member function checklogin() from class **LDAP **is always failing. I am not sure, what the problem is. But i think, the way it looses the data is when redirect happens. ".../oauth/authorize.php 302"

My testldap.php is written on similar code to LDAP.php but without any object oriented programming.
And this is working. And all was fine before the patches and upgrade.

I always setup the extra host ip for docker-compose of each conatiner, so that container "mattermost" contains the ip of container "webserver"

I am very sure with my Gitlab section in config.json of Mattermost-Server.

        "AuthEndpoint": "http://webserver-ip/oauth/authorize",
        "TokenEndpoint": "http://webserver-ip/oauth/token.php",
        "UserAPIEndpoint": "http://webserver-ip/oauth/resource.php",

Error: LDAP Operation error ".../oauth/LDAP/LDAP.php - 118"

To Reproduce
Steps to reproduce the behavior: look to the description.

Workaround: Temporarily away from OOP. That works!