Have you tried to use XSLT? I think you can remove that XML Declaration by setting omit-xml-declaration="yes". Ref: https://www.w3schools.com/xml/ref_xsl_el_output.asp
 

Hi Alexander,

There is some information about debugging SSL/TLS connections using REDEBUG utility here: https://community.intersystems.com/post/ensemble-201523-certificate-not…

It may be helpful.