Jmix application libreoffice error

installed libreoffice on my ubuntu server. But the other jmix applications on the server cannot use it . Example: they can’t use it to download a report in pdf format. The error is shown below. what is the possible solution?
ReportingException: Unable to convert to calc_pdf_Export. All attempts failed Report name [“Salary payscale pr line” Report (PAYSLIP) ]
Unable to create Open office components.
io.jmix.reports.yarg.formatters.impl.doc.connector.BootstrapException: Unable to connect to the OO process
Unable to connect to the OO process
java.net.ConnectException: Connection refused