Mobile photo downloads fail through nginx HTTPS

upstream primary {
    server localhost:2283;
}

server {
    listen 443;
    server_name photos.example.com;

    ssl on;
    ssl_certificate /etc/ssl/star_example_com_chain.crt;
    ssl_certificate_key /etc/ssl/private/star_example_com.key;

    client_max_body_size 50000M;

    proxy_set_header Host              $http_host;
    proxy_set_header X-Real-IP         $remote_addr;
    proxy_set_header X-Forwarded-For   $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;

    proxy_http_version 1.1;
    proxy_set_header   Upgrade    $http_upgrade;
    proxy_set_header   Connection "upgrade";
    proxy_redirect     off;

    proxy_read_timeout 600s;
    proxy_send_timeout 600s;
    send_timeout       600s;

    location / {
        proxy_pass http://primary;
    }
}