Ignore the powerline adapter and connect directly to your router's LAN ports.
I can't get my LaserJet 100 connected to my network via Ethernet (working via WiFi but would prefer to switch to Ethernet). The manual says the lights by the Ethernet port should be lit when connected and those lights are not lit on my printer. Printed Network Summary shows "Status = Not Connected" for Wired Network Configuration. In case it's relevant, I'm using a Powerline Ethernet adapter, which has no issues connecting other devices.