Openvpn ldap (Active Directory) authentication - Incorrect password supplied for LDAP
Solution 1:
The log indicates LDAP Bind Failed, so it is not reaching the point that user-credentials may be evaluated.
The BindDN appears unusual: BindDN CN=user1,CN=users,DC=izmir,DC=com,DC=tr
At a guess, perhaps that should be: BindDN CN=user1,OU=users,DC=izmir,DC=com,DC=tr
Suggest verifying the DN of the account. Swapping CN for OU in the BindDN will result in the behavior observed. Otherwise, verify the credentials.