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If I'm at the library.

And there are Ethernet ports.

Desktop computers are connected to it and working fine.

But when I try to unplug it and connect my laptop with it it's just doesn't work, as if it says there is no Ethernet connection at all.

What are some of the reasons for such thing?

Do I have to look up specific IP configuration and configure it on my laptop?

Do these windows domain system matter?

How can I get started figuring why it says it's that there's no connection in the first place?

The librarians know Jack shit about why it's not working.

And I can't find the technician contact address to ask him/her/them directly.

WiFi works fine, but slow, Ethernet connections has a gigabit connection. (I believe that should explain why I want to use that instead)

Comments
  • 4
    to explain @zlice comment:
    if the switch/router sees that a mac changes abruptly it shut the port down. if the admin configured it, it checks at regular intervals if the old mac reappears and open the port again. if not the admin must reopen the port manually.
  • 1
    @cabrasm

    @Revenger said "But when I try to unplug it and connect my laptop with it it's just doesn't work, as if it says there is no Ethernet connection at all."

    If the DHCP had an MAC-Filter the error Message would say this. Mac-Security powers the port off. Its like the cable would not be connected.
  • 1
    My university has that too. They have a list of the MAC addresses of the computers that are allowed, so in order to connect through Ethernet, you just change the MAC address of your laptop, and should work. On linux:
    ifconfig eth0 down
    ifconfig eth0 hw ether NEW:MAC:ADDRESS
    ifconfig eth0 up
    (I think you need to be root, so probably prepend sudo, and of course, change eth0 to whatever your ethernet interface is)
    It does not stay across reboots, so you will have to do it each time.
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