I add more information and a question:

From within the PC-Server:

(base) marco@pc:~$ curl -Iki https://localhost/sockjs-node/info?t=1580397983088
HTTP/2 405
server: nginx/1.14.0 (Ubuntu)
date: Fri, 31 Jan 2020 08:19:02 GMT
allow: OPTIONS, GET

From the laptop:

(base) marco@marco-U36SG:~$ curl -Iki https://ggc.world/sockjs-node/info?t=1580397983088
HTTP/1.1 405 Method Not Allowed
Server: nginx/1.14.0 (Ubuntu)
Date: Fri, 31 Jan 2020 09:34:59 GMT
Connection: keep-alive
Allow: OPTIONS, GET

What does it mean "HTTP/1.1 405 Method Not Allowed" ?