Have you tried browsing to https://nodejs.mydomain.com/demo/index.html The proxy configuration in Apache will direct the connection to nodejs over port 8000.
172.16.16.45 - drupaladmin [21/Jun/2023:23:04:07 +0530] "GET /demo/index.html HTTP/1.1" 404 25644 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36"
172.16.16.45 - drupaladmin [21/Jun/2023:23:04:18 +0530] "GET /demo/index.html HTTP/1.1" 404 25644 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36"
172.16.16.45 - drupaladmin [21/Jun/2023:23:04:39 +0530] "GET /demo/index.html HTTP/1.1" 404 25644 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36"
Please suggest further. Thanks in advance.
Best Regards,
Kaushal