https://bugs.openldap.org/show_bug.cgi?id=10080
--- Comment #8 from Ondřej Kuzník ondra@mistotebe.net --- The right way around would probably be to use back-meta, which has rewrite functionality built in so syncprov doesn't have to suffer from what rwm has to do to the operation structure when it's configured as an overlay.
A brief outline (slapd.conf style because that's easier for intent):
database meta suffix ou=remote,ou=users,dc=example,dc=com
uri ldaps://dc1.example.com/ou=remote,ou=users,dc=example,dc=com suffixmassage "ou=remote,ou=users,dc=example,dc=com" "ou=users,dc=ad,dc=example,dc=com" idassert ...