Hi,
regarding the first warning please have a look at How-to: Handle s4-connector rejects.
We also get the second warning. It is caused by a modification of /etc/ldap/slapd.conf by Open-Xchange. I think there is break missing at the end of these lines which could be solved by editing /etc/univention/templates/files/etc/ldap/slapd.conf.d/66oxforucs.acl, but I think this should be done by UCS/Open-Xchange and not us users.
Best,
Andreas