Longboardcruiserspt.free.nf in visible to me only with VPN connection

[EdwardHamHam]

That doesn’t really help because that online tool does a traceroute from the server powering centralops.net, not your own network.

@SimpleInfinity

I’m using Linux.

Which distro? If it’s an Ubuntu or Debian-based distribution, you should be able to install the traceroute utility from APT and then use it with this command in the terminal:
traceroute longboardcruiserspt.free.nf

@Greenreader9

Unfortunately you can’t use traceroutes to test the connection to free hosting as the servers block those requests (As well as ping requests)

True, but it can still be helpful in this situation, as the connection being blocked at the network level or by the ISP would still terminate before even getting to the web server.

@Admin

This is irrelevant, because the security system only restricts web requests, not tracerts. Tracerts work with ping, so you’ll be unable to trace the full path. But if you can see in the traceroute that your traffic never reaches our datacenter, then you definitely know something is wrong.