Is there a way for me to, say, open up just one port, like 25565, and allow users to connect to my other minecraft servers, let's say hosted on 25566 and 25567 with subdomains?
This generally depends on whether the protocol allows clients to specify which domain they want (such as the "Host:" header in HTTP or the "Server Name Indication"...
It is possible to install Raspberry PI OS on an SD card using only a Chromebook.
Put Raspberry PI OS on SD Card
It is possible to configure a WiFi enabled Raspberry Pi using only a
Chromebook and your WiFi access point. This can be done headless (no
monitor required) and results in a Raspberry Pi with WiFi and ssh
enabled so that you can control it from ...
And then I tried to access my server and it worked on my desktop browser (although it takes a while to get response) but when I tried to visit website on my mobile phone it only works when I define port 3000 in address. Also when on my desktop browser I define port :3000 in address bar the response is instant.
My first suspicion is that your server has both ...
This would cause a huge amount of useless data going through the network.
Well, that's exactly why they don't reply.
This is stated as an explicit requirement in RFC 1122 ("Requirements for Internet Hosts -- Communication Layers"), section 3.2.2, and the commentary specifically points out UDP broadcasts as the reason:
An ICMP error message ...
There is a common misconception about the IANA port registration.
The only reason this list exists is to avoid conflicts with
Nothing stops you from using any one port from the list if you have
not installed the software that uses it by default. And even then,
you may set that software to use another port (if possible).
I wouldn't advice ...