One of my players is getting a "can't resolve host" error and I am stumped

[MrHoatzin]

Heyo friends,

I've had 20+ people connect to a box that I am hosting in a closet at the school without issues. Latency is great and the server is seldom sluggish under load. Most people are local (Texas), but some have connected from Florida and Hawaii without issues. It is an unlisted server I'm hosting for my students.

One student however is getting a "can't resolve host" error, whether he uses the domain name or the IP address. He can run a local game or connect to a random public server on the list just fine. He shared his screen via Zoom and I carefully observed what he was doing; he was not making any obvious typos or whatever. He was running a freshly downloaded Minetest (v5.3) on a Windows 10 machine.

I am stumped as to how to begin troubleshooting this one. I sent him instructions on how to run a tracert, but my own traceroute to the server is timing out (???) even tho I can connect just fine within a few seconds.

[Festus1965]

let him do a tracert or mtr to see where he stuck,
and ask school firewall if have IP entries to block some ...
last he should do the same test from another location, maybe at a friend who CAN connect

[Bastrabun]

What does your server say? Does it see his connection attempts or do they not even reach your box?

What kind of server is that? Raspberry pi? Linux box? Something Window-ish?

To see whether its a Minetest issue you can run some other service on the box, like a webserver or something, then have him try to connect to this one. Everything alright? -> MT issue. Also no connection? Most likely connection issue.

Neither you nor he can properly tracert to the machine? Probably on some network that forbids it. Any other hosts on the same network he could ping/trace, to rule out the school firewall?

Is your MT server configured to accept IPv6? Which IP version does he try to connect with? What do the others use?

[sorcerykid]

That's a very interesting error message, particularly if he's entering the IP address rather than a domain name. Something is definitely amiss, and I'd consider opening an issue on GitHub.

[MrHoatzin]

So middle schoolers are bad at following directions. The pandemic surely doesn't help. I asked him to try a library wifi or a different computer and see if he gets the same message. I keep asking him to do the troubleshooting outside of class time so that we can run all the things and he keeps showing up for the class unprepared and is all "what now" and I still don't have traceroute info from him.

However, I have confirmed that he is getting the "can't resolve host" error with the IP address typed in. He is the only person of 30 who cannot connect. The server is a macMini. It is not a usual school, it is an after-school art program, so we have a lot of control over the infrastructure. We don't block anything summarily in or out on the network. The IT dude set it up so that anyone connecting to port 30000 goes straight to the box. I manage the box via VPN and remote desktop just fine. I'm pretty sure it is not a connection issue, at least not at any normal point on our controllable end.