A directory may have entries with thousands of child entries. It is not recommended to fetch all these children when browsing because this increases directory and network load and is very time consuming.
It is recommended to limit the number of returned entries. The limit is defined in Connection properties.
Another option is to use a filter to limit the fetched children. Choose Filter Children... from context menu. In the opened dialog you could define a LDAP filter. Hit Strg-Space to get content assistance. The drop-down list provides a history of recently used filters. A click to the Filter Editor button opens the Filter Editor dialog.