I finally found this again. I had seen it,wanted to share it but got interrupted, and had not saved the url:
https://www.openbsd.org/httpd.conf
Not knowing what you are trying to do exactly makes it hard to suggest much, however you might be able to use the above as a guide and template, modify to suit your needs,
Note, in the code they use, no where do they use a line like what you have:
Code:
fastcgi param HTTP_HOST "test.example.com"
In fact, you might try with out that line a see what you get as well,...with out seeing the entire httpd.conf , it is hard to say.
You should also see this:
https://man.openbsd.org/bgplg.8
It may be of help to you.