Thanks for your reply! We kind of got a working setup but still there is something unclear to me. Please find our updates below:
For the eth0 (port 6 in the figure below), there was some contradicting issue with the default IP address when connect to our university network, and we got it fixed. Now we can get connection to the university Internet via the port with DHCP setting. However, when I connect port 6 to our Kuka robot controller (a static address), it still cannot recognize the connection (GUI shows cable unplugged, and ifconfig same as above), even with the correct static address.
We tried to use an usb-c to ethernet adapter connected via port 10, and we got eth1 in ifconfig (so eth0 is the physical interface port 6, and eth1 is the usb-c port 10 connected with an ethernet adapter). This eth1 interface worked (connected to the robot controller) straight away.
We are probably good to go with current setup but I am just a bit confused why it works with eth1 but not eth0. If anyone knows the cause please let me know. Thanks!
Cheers,
J