Issue with NGINX and proxy: HTTP/1.1 505 HTTP Version not supported

[Willy Gardiol]

Hi all!
first time poster here so please excuse my manners and correct me where 
i am wrong.

I use NGINX 1.16.1 on Gentoo as reverse proxy server to expose some 
services to an external web site.

I am exposing many things but one is giving me headaches.

I am trying to expose the web UI of an HP network printer.

I have this in my nginx.conf (trimming lines to the ones relevant):
server {
                 listen 80;
                 access_log /var/log/nginx/localhost.access_log main;
                 error_log /var/log/nginx/localhost.error_log debug;

                 location /printer/ {
                         proxy_pass http://192.168.1.XX/;
                 }
}

I can access the printer from the proxy server, no problems, with:
curl http://192.168.1.XX

But if i try, on the same proxy server this:
curl http://127.0.0.1/printer/

I get the error:
2020/03/06 08:42:02 [debug] 12870#0: *2 connect to 192.168.1.XX:80, 
fd:11 #3
2020/03/06 08:42:02 [debug] 12870#0: *2 http upstream connect: -2
2020/03/06 08:42:02 [debug] 12870#0: *2 http finalize request: -4, 
"/printer/?" a:1, c:2
[snip]
2020/03/06 08:42:02 [debug] 12870#0: *2 http run request: "/printer/?"
2020/03/06 08:42:02 [debug] 12870#0: *2 http upstream check client, 
write event:1, "/printer/"
2020/03/06 08:42:02 [debug] 12870#0: *2 http upstream request: 
"/printer/?"
2020/03/06 08:42:02 [debug] 12870#0: *2 http upstream send request 
handler
2020/03/06 08:42:02 [debug] 12870#0: *2 http upstream send request
2020/03/06 08:42:02 [debug] 12870#0: *2 http upstream send request body
[snip]
2020/03/06 08:42:02 [debug] 12870#0: *2 http upstream request: 
"/printer/?"
2020/03/06 08:42:02 [debug] 12870#0: *2 http upstream process header
[snip]
2020/03/06 08:42:02 [debug] 12870#0: *2 http proxy status 505 "505 HTTP 
Version not supported"
2020/03/06 08:42:02 [debug] 12870#0: *2 http proxy header: 
"X-Content-Type-Options: no-sniff"
2020/03/06 08:42:02 [debug] 12870#0: *2 http proxy header: 
"Cache-Control: no-cache, no-store, must-revalidate"
2020/03/06 08:42:02 [debug] 12870#0: *2 http proxy header: "Server: 
gSOAP/2.7"
2020/03/06 08:42:02 [debug] 12870#0: *2 http proxy header: 
"Content-Length: 0"
2020/03/06 08:42:02 [debug] 12870#0: *2 http proxy header: "Connection: 
close"
2020/03/06 08:42:02 [debug] 12870#0: *2 http proxy header done
2020/03/06 08:42:02 [debug] 12870#0: *2 HTTP/1.1 505 HTTP Version not 
supported^M

So my guess NGINX is doing something which the web printer does not 
like...

What could i try or do?

thank you for your time and response.





-- 
Willy Gardiol
willy at gardiol.org
www.gardiol.org
www.trackaway.org -> Track YOUR way the way you want!