ldap_unbind kills the link descriptor.  So, if you want to rebind as another user, just bind again; don't unbind.  Otherwise, you'll have to open up a new connection.(PHP 4, PHP 5, PHP 7, PHP 8)
ldap_unbind — Unbind from LDAP directory
| Версія | Опис | 
|---|---|
| 8.1.0 | 
  Тепер параметр ldap має бути примірником
  LDAP\Connection; раніше очікувався дійсний resource
  ldap link.
  | 
ldap_unbind kills the link descriptor.  So, if you want to rebind as another user, just bind again; don't unbind.  Otherwise, you'll have to open up a new connection.