Hi Maxim, thanks for your input.

I had, in the meantime, added the directives

gzip_http_version 1.0
gzip_vary on


Does the fact that the response contains this header

Via:1.1 localhost.localdomain

mean that HTTP 1.1 is being used? Having changed temporarily the gzip_proxied directive to

gzip_proxied any

hasn't changed a thing, unfortunately. I will look in more detail at the gzip_proxied values and see how they are applicable or not.

Thanks,
Jakob.