net::ERR_CONNECTION_REFUSED . How to correctly configure Nginx with Socket.io?

[MarcoI]

>From within the PC-Server:

(base) marco at pc:~/vueMatters/testproject$ curl -vk
https://localhost/sockjs-node/info?t=1580397983088
*   Trying ::1...
* TCP_NODELAY set
* connect to ::1 port 443 failed: Connection refused
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* successfully set certificate verify locations:
*   CAfile: /etc/ssl/certs/ca-certificates.crt
  CApath: /etc/ssl/certs
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Unknown (8):
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Certificate (11):
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, CERT verify (15):
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Finished (20):
* TLSv1.3 (OUT), TLS change cipher, Client hello (1):
* TLSv1.3 (OUT), TLS Unknown, Certificate Status (22):
* TLSv1.3 (OUT), TLS handshake, Finished (20):
* SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384
* ALPN, server accepted to use h2
* Server certificate:
*  subject: CN=ggc.world
*  start date: Nov 30 11:22:10 2019 GMT
*  expire date: Feb 28 11:22:10 2020 GMT
*  issuer: C=US; O=Let's Encrypt; CN=Let's Encrypt Authority X3
*  SSL certificate verify ok.
* Using HTTP2, server supports multi-use
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade:
len=0
* TLSv1.3 (OUT), TLS Unknown, Unknown (23):
* TLSv1.3 (OUT), TLS Unknown, Unknown (23):
* TLSv1.3 (OUT), TLS Unknown, Unknown (23):
* Using Stream ID: 1 (easy handle 0x559bc64c5580)
* TLSv1.3 (OUT), TLS Unknown, Unknown (23):
> GET /sockjs-node/info?t=1580397983088 HTTP/2
> Host: localhost
> User-Agent: curl/7.58.0
> Accept: */*
> 
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* TLSv1.3 (IN), TLS Unknown, Unknown (23):
* Connection state changed (MAX_CONCURRENT_STREAMS updated)!
* TLSv1.3 (OUT), TLS Unknown, Unknown (23):
* TLSv1.3 (IN), TLS Unknown, Unknown (23):
< HTTP/2 200 
< server: nginx/1.14.0 (Ubuntu)
< date: Fri, 31 Jan 2020 14:00:47 GMT
< content-type: application/json; charset=UTF-8
< access-control-allow-origin: *
< vary: Origin
< cache-control: no-store, no-cache, no-transform, must-revalidate,
max-age=0
< strict-transport-security: max-age=31536000
< 

>From the laptop:

(base) marco at marco-U36SG:~$ curl -vk
https://ggc.world/sockjs-node/info?t=1580397983088
*   Trying 2.36.58.214:443...
* TCP_NODELAY set
* Connected to ggc.world (2.36.58.214) port 443 (#0)
* ALPN, offering http/1.1
* successfully set certificate verify locations:
*   CAfile: /home/marco/anaconda3/ssl/cacert.pem
  CApath: none
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* 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 to use http/1.1
* Server certificate:
*  subject: CN=ggc.world
*  start date: Nov 30 11:22:10 2019 GMT
*  expire date: Feb 28 11:22:10 2020 GMT
*  issuer: C=US; O=Let's Encrypt; CN=Let's Encrypt Authority X3
*  SSL certificate verify ok.
> GET /sockjs-node/info?t=1580397983088 HTTP/1.1
> Host: ggc.world
> User-Agent: curl/7.65.2
> Accept: */*
> 
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* old SSL session ID is stale, removing
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Server: nginx/1.14.0 (Ubuntu)
< Date: Fri, 31 Jan 2020 14:04:11 GMT
< Content-Type: application/json; charset=UTF-8
< Transfer-Encoding: chunked
< Connection: keep-alive
< Access-Control-Allow-Origin: *
< Vary: Origin
< Cache-Control: no-store, no-cache, no-transf

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,286850,286879#msg-286879