Nginx as local network proxy with Lets encrypt and Duckdns doesn't work after upgrade

[komzi2920]

Checklist

• Have you pulled and found the error with jc21/nginx-proxy-manager:latest docker image?
  • Yes
• Are you sure you're not using someone else's docker image?
  • Yes
• Have you searched for similar issues (both open and closed)?
  • Yes

Describe the bug

I'm not sure if this a bug.
I have updated my container which was configured with SSL and Duckdns to manage local hosts in my home network, but now I cannot access them via https protocol because I get now always 504 timeout error.
I have increased the timeout for the parameters listed below in nginx.conf file and now I'm getting a different error 502 Bad Gateway.
proxy_connect_timeout 300s;
proxy_send_timeout 300s;
proxy_read_timeout 300s;

Below is show the curl command output when trying to test https connection with my host xx @Domain yy.duckdns.org

#####################################
curl -v https://xx.yy.duckdns.org

• Trying 192.168.zz.tt:443...
• Connected to xx.yy.duckdns.org (192.168.zz.tt) port 443 (#0)
• ALPN: offers h2,http/1.1
• TLSv1.3 (OUT), TLS handshake, Client hello (1):
• CAfile: /etc/ssl/certs/ca-certificates.crt
• CApath: /etc/ssl/certs
• TLSv1.3 (IN), TLS handshake, Server hello (2):
• TLSv1.3 (IN), TLS handshake, Encrypted Extensions (8):
• TLSv1.3 (IN), TLS handshake, Certificate (11):
• TLSv1.3 (IN), TLS handshake, CERT verify (15):
• TLSv1.3 (IN), TLS handshake, Finished (20):
• TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1):
• TLSv1.3 (OUT), TLS handshake, Finished (20):
• SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384
• ALPN: server accepted http/1.1
• Server certificate:
• subject: CN=*.yy.duckdns.org
• start date: Aug 21 19:58:32 2025 GMT
• expire date: Nov 19 19:58:31 2025 GMT
• subjectAltName: host "xx.yy.duckdns.org" matched cert's "*.yy.duckdns.org"
• issuer: C=US; O=Let's Encrypt; CN=E8
• SSL certificate verify ok.
• using HTTP/1.1

GET / HTTP/1.1
Host: xx.yy.duckdns.org
User-Agent: curl/7.88.1
Accept: /

• TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
• TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
• old SSL session ID is stale, removing
  < HTTP/1.1 502 Bad Gateway
  < Server: openresty
  < Date: Thu, 21 Aug 2025 21:33:27 GMT
  < Content-Type: text/html
  < Content-Length: 154
  < Connection: keep-alive
  <

<title>502 Bad Gateway</title>

502 Bad Gateway

---

openresty * Connection #0 to host xx.yy.duckdns.org left intact 502 Bad Gateway502 Bad Gateway

Can you please help me how to resolve this ?

Thanks !

Nginx Proxy Manager Version

v2.12.6

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Expected behavior

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Operating System

Additional context