I have made 3 different types of extremely simple servers on a remote port:
I tested each separately, connecting them to the same port (call this port 9005). They only used the code linked above, modifying ports where necessary. When I connect to my remote server using my laptop (terminal and/or browser), 1 and 2 work, yet 3 does not.
Since 1 and 2 work, I thought there would not be any firewall issues, but could there still be some? Since - for instance - 1 and 2 are Java but Node.js is Javascript.