Nginx reverse proxy regex help

[blason]

Hi Team,

I have server whose URL is https://xx.xx.xx.xx/TestPage/ which gets
generated as

https://xxxx.xxx.xxx/TestPage/(S(0inoxzi14rxqq1uix1tiyp1t))/index.aspx

Now I have implemented nginx reverse proxy in front this server and then I
have done the config proxy_pass as 

proxy_pass https://xxx.ssss.sss.ss/TestPage;

Now if you see after TestPage there is a unique value gets added and then
index.aspx however whenever request is passed through nginx I get 502
badgateway.

Wondering how do I pass that unique value through regex? 

Please help

here is lcoation

location /TestPage {
        client_max_body_size    10m;
        client_body_buffer_size 128k;
        proxy_send_timeout   90;
        proxy_http_version 1.1;
        proxy_read_timeout   90;
        proxy_buffer_size    128k;
        proxy_buffers     4 256k;
        proxy_busy_buffers_size 256k;
        proxy_temp_file_write_size 256k;
        proxy_connect_timeout 30s;
        proxy_pass https://xx.ss.xx.ss/TestPage;
        proxy_redirect default;
        proxy_set_header   Host   $host;
        proxy_set_header   X-Real-IP  $remote_addr;
        proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
        add_header Strict-Transport-Security "max-age=31536000;
includeSubDomains" always;
        add_header X-Content-Type-Options nosniff;
        add_header X-XSS-Protection "1; mode=block";
        add_header Referrer-Policy "no-referrer-when-downgrade";
        }
}

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,292405,292405#msg-292405