HTTP Host Header?

I am a newbie to AppGyver currently trying to set up a data connector to a restful service.
The service requires the Host header. If it doesn’t match the source of the request then it gets rejected
(On postman this would present as: Hostname/IP does not match certificate’s altnames)
However, I don’t know, nor can I find out what the hostname is that I should be sending from appgyver. I have tried but that doesn’t work.

Can someone advise the hostname that the Composer Data Resource actually uses.
It would be good to have this as an autogenerated optional header.

Any help would be appreciated.

Just to add some clarity, I have this API call working via postman. and the only difference is the Host Header entry… that’s why I think I’ve isolated it to this.