http_sub_module / sub_filter of nginx and reverse proxy not working
Check if the upstream source has gzip turned on, if so you need proxy_set_header Accept-Encoding “”; so the whole thing would be something like location / { proxy_set_header Accept-Encoding “”; proxy_pass http://upstream.site/; sub_filter_types text/css; sub_filter_once off; sub_filter .upstream.site special.our.domain; } Check these links https://www.ruby-forum.com/topic/178781 https://forum.nginx.org/read.php?2,226323,226323 http://www.serverphorums.com/read.php?5,542078