Thanks for your answer 
By default the Yunohost LDAP server bind only on 127.0.0.1, i search how to open it on other. (edit : FALSE)
After i don’t know if the clients need can access to LDAP server or only other server (nextcloud etc). If it’s only other server i wan’t my LDAP server listen on VPN adress (10.8.0.x)
ps : sorry for my bad english
Edit : ok i have open the port '(389) ine the firewall, other machine can look it via nmap.
Now in my nextcloud i need push DN User, password and “base DN” (?) i search it in config file (/etc/ldap/)
In /etc/ldap/slapd.d/cn=config/olcDatabase={1}mdb.ldif their is interessing lines:
olcSuffix: dc=yunohost,dc=org
olcAccess: {0}to attrs=userPassword,shadowLastChange by dn.base=“cn=admin,d
> c=yunohost,dc=org” write by anonymous auth by self write by * none
olcAccess: {1}to attrs=cn,gecos,givenName,mail,maildrop,displayName,sn by d
n.base=“cn=admin,dc=yunohost,dc=org” write by self write by * read
olcAccess: {2}to dn.base=“” by * read
olcAccess: {3}to * by dn.base=“cn=admin,dc=yunohost,dc=org” write by group
/groupOfNames/member.exact=“cn=admin,ou=groups,dc=yunohost,dc=org” write b
y * read
OK, IT’S WORK
Login : cn=admin,dc=yunohost,dc=org
Password : your admin password defined during “post-installation”
for opening, just opening 389 TCP port in your firewall (tuto in french). i write a tuto for nextcloud integration in french, i translate after and post the link
PS : install iptables-persistent have totaly crash my yunohost installation (debian jessie), anybody know how i can save iptable rull (iptables -A INPUT -p tcp --dport 389 -s 10.8.0.0/24 -j ACCEPT)?