Accessing TP-LINK TL-SG1016PE switch behind reverse proxy

Question

I am trying to access my switch through my Nginx reverse proxy. I can access the switch fine using the local ip over http, but when I try with the domain name through my reverse proxy with over https, I can get the login page, but when I enter my credentials and click login the page times out (error 502). The issue seems to be with the logon.cgi page.

Would anyone know how to correctly configure a reverse proxy for this switch? (I have similar configuration working for my TP-Link router and many other services)

Here is my simple reverse proxy configuration:

server {    
    listen 80 default_server;
    listen [::]:80 default_server;
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl http2;
    server_name switch.example.com

    ssl_certificate ...
    ssl_certificate_key ...

    access_log            /var/log/nginx/switch.access.log;
    error_log            /var/log/nginx/switch.error.log;


    location / {

        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-Host $host;
        proxy_set_header X-Forwarded-Server $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_buffering off;
        client_max_body_size 0;
        proxy_connect_timeout  3600s;
        proxy_read_timeout  3600s;
        proxy_send_timeout  3600s;
        send_timeout  3600s;

        proxy_set_header X-NginX-Proxy true;

 

      proxy_pass  http://192.168.1.2;
      proxy_redirect http://192.168.1.2 https://switch.example.com;
    }

I have tried to debug using the browser dev tools but I really don't understand what is wrong. Using hard DNS mapping from switch.example.com to 192.168.1.2 works, and here is what I see in the dev tools for the login script:

Request URL: http://switch.example.com/logon.cgi
Request Method: POST
Status Code: 200 OK
Remote Address: 192.168.1.2:80
Referrer Policy: strict-origin-when-cross-origin
Connection: close
Content-Type: text/html
Transfer-Encoding: chunked
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Cache-Control: max-age=0
Connection: keep-alive
Content-Length: 53
Content-Type: application/x-www-form-urlencoded
Host: switch.example.com
Origin: http://switch.example.com
Referer: http://switch.example.com/
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/101.0.4951.67 Safari/537.36 OPR/87.0.4390.45

But when I try to access the switch through my reverse proxy (setting a CNAME that points to my nginx server), here's what I see:

Request URL: https://switch.example.com/logon.cgi
Referrer Policy: strict-origin-when-cross-origin
:authority: switch.example.com
:method: POST
:path: /logon.cgi
:scheme: https
accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
accept-encoding: gzip, deflate, br
accept-language: en-US,en;q=0.9
cache-control: max-age=0
content-length: 53
content-type: application/x-www-form-urlencoded
origin: https://switch.example.com
referer: https://switch.example.com/
sec-ch-ua: " Not A;Brand";v="99", "Chromium";v="101", "Opera";v="87"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Windows"
sec-fetch-dest: document
sec-fetch-mode: navigate
sec-fetch-site: same-origin
sec-fetch-user: ?1
upgrade-insecure-requests: 1
user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/101.0.4951.67 Safari/537.36 OPR/87.0.4390.45

Also, I have used WireShark to capture the request when I successfully login using the local ip address (http://192.168.1.2): Wireshark screenshot (Sorry for the link, not enough rep)

Looking at the Nginx error log, I see it is a timeout error:

the error from the Nginx reverse proxy is a timeout error:

2022/06/10 16:53:54 [error] 3630#3630: *29 upstream timed out (110: Unknown error) while reading response header from upstream, client:
192.168.1.123, server: switch.example.com, request: "POST /logon.cgi HTTP/2.0", upstream: "http://192.168.1.2:80/logon.cgi", host: "switch.example.com", referrer: "https://switch.example.com/"