HP Elitedesk 800 G4/G5 FlexPort Ethernet
Based on a design by https://www.thingiverse.com/nateronipizza, changed ever so slighty to make it work with this: https://www.ebay.de/itm/256332367512
Use 2 M3x12 bolts (secured from the back) to secure the port to the holder, as seen on the photos.