First of all, I would like to clarify that I have very little knowledge about operating systems and computing in general, which unfortunately prevents me from using technical terms. For my (biology) internship I had to install Ubuntu on a empty server. I installed Ubuntu Server 22.04 using a bootable USB made with Rufus (created by following the tutorial from Ubuntu). After installation, Ubuntu couldn't connect to the ethernet and find the IPv4 or IPv6 adresses which were shown during booting. After booting, I got the following output while running dhclient:
No DHCPOFFERS received. No working leases in persistent database - sleeping
While trying to find a solution to the problem, I also got the following by running ip -a:
eno1:<NO-CARRIER,BROADCAST,MULTICAST,UP> ....

I tried rebooting as well as running dhclient -v -r followed by dhclient -v but this didn't change anything. I also tried a different cable in order to fix the NO-CARRIER, but this also didn't work.

Running cat /etc/netplan/*.yaml gives the following output:

network:

  ethernets:

    eno1:

      dhcp4: true

    eno2:

      dhcp4: true

    eno3:

      dhcp4: true

    eno4:

      dhcp4: true

    version: 2