After trying out the suggestions [here](https://askubuntu.com/questions/1078539/hdmi-port-not-detected-on-ubuntu-18-04), which did not solve my issue, I decided to ask the question:

I have a freshly installed Ubuntu 18.04 LTS on my Thinkpad T14, but I can not connect to an external monitor via HDMI cable. I tried it with 2 different displays so the source of the problem should be on the laptop side.

Can someone help me out solving it? Thanks in advance!