I'ver never worked with any Raspberry model before and now one of my university courses requires me to. Since I don't have any spare peripheral devices to connect the raspberry to I'm trying to access it via my windows laptop. Now the problems already began when I tried to connect it to my router directly via Ethernet-cable. The raspberry doesn't show up on my routers configuration page and I can't find it by scanning my network for devices.
Is there anything I can do in this situation?
on boot the green ACT starts flickering and stops after a few seconds
Sounds good. This means the pi has at least booted the OS. I'm presuming below that you are using Raspbian or some other GNU/Linux distro.
Note that the first time you boot Raspbian, it expects to guide you through a configuration process. Although I don't think this should have impacted the ethernet connectivity, I can't say for sure.
the ethernet leds (orange and green) are lit while the raspi is connected to the router.
I believe this indicates there is a good link layer connection between the pi and the router.
Is there anything I can do in this situation?
Since this is for university, you might as well try to diagnose this with some standard low level tools. After completing the configuration process mentioned above, start by disabling network autoconfiguration; it is evidently not working for you anyway.
Reboot, then check the output of ip link. It should mention two interfaces, lo and eth0; the latter will be state DOWN. Set it up with:
sudo ip link set eth0 up
Presuming your router uses DHCP, you should now be able to get an IP with:
sudo dhclient -v eth0
This may take a few seconds and it will spit lines about discovery and obtaining a lease, then exit into the background. You can double check the assigned address with ip addr.
At that point the pi should be visible on the router interface. If the LAN is not isolated you should be able to, e.g., ping 8.8.8.8. If that works, try ping google.com; if that works you have an IP and DNS, i.e., normal internet.
