I would check the username, like Jeff suggested. I have a few questions about your setup.
Other than security.properties did you modify other configuration files?
Since you mentioned your LDAP domain, are you integrating with an existing LDAP instance? If you’re not, then you don’t need to modify any of the LDAP fields in security.properties. If you’re, security.server.ldapDomainDClevel3 would not allow you to specify your full domain. It is not a valid configuration key. You need to specify the full address, see my reply in Problem installing ODKv2 Sync on Ubuntu with Custom LDAP (AD) - yaml: line 98: did not find expected key - #3 by linl33
And note that the security.server.ldapDomain* fields are only for Active Directory authentication not for standard LDAP. (sync-endpoint-default-setup/config/sync-endpoint/security.properties at 53f56c187c330434e1dbefa6b99394859d16df10 · odk-x/sync-endpoint-default-setup · GitHub)