After upgrading Ubuntu 16.04 LTS to 20.04 LTS on my Zotac Nano HTPC the remote control did not work anymore. After quite some investigation it seemed that the the problem lies within a version bump of LIRC.
I decided to revert back to lirc 0.9.0-0ubuntu6 and reconfigure my remote using the following steps:
First remove any existing installations of ir-keytable and lirc.