Re: nginx proxy to subdirectory

Have a good look at the logfiles, what is being requested and what is being passed on to the backend, often when using a debug build and the debug log you can see the re-write happening and figure out what the config is doing when it is parsed.

location /site1 {
proxy_pass http://192.168.1.10:80;
}

or,

location /site1/ {
rewrite /site1/([^/]+) /$1 break;
proxy_pass http://192.168.1.10:80/;
}