@csoltenborn 

Hi,

If you intend to open up a device that works on mains voltage (depending on the country 110-120V or 220-240V), then you won't get much advise in an official forum like this, because working on this stuff is dangerous for anyone who hasn't been specially trained. 

If you are sure you will never want to use the Ethernet ports on that device ever again, then you might consider filling the Ethernet sockets with hot glue using a hot glue gun, like those used by children to do handicrafts. That could be done without opening the device and also be fairly secure. I can't see anyone going through the effort of removing all that glue (without damaging the fine contacts) well enough to be able to connect a RJ45 cable again.