DTD declaration in XML response - Rest connector - RTC Server

Hello,
I am trying to make a rest connection to an on-premise RTC version 6.0.6.0 using Qlik Sense (Business Intelligence and Visualisation tool).
When I connect to this endpoint /rpt/repository/foundation?fields=projectArea/projectArea/name
on the trial Jazz server online I can get the XML response. But the customers on premise server returns a DTD declaration which prevents the process.
Just wondering if there is a configuration or something that would be stopping me.
I have set DTD ignore in Qlik Sense, but that didnt resolve the issue.
Thank you,
Clint Carr