Comment by Kamil Maciorowski on Outbound connections blocked by the ghost of a recently departed IP address

(1) "during the full period of a RPi reboot" – So the problem does survive reboots, right? This should be clearly stated. (2) "I have run grep against every file in /etc/ and all its sub directories" – What was the exact command? // Please respond by [edit]ing the question, not in comments.