If the attacker renew ip, no good block, best option is to replace the doors.
better yet make a SCNA port on your pc with nmap-sV [ip] check their doors open and change.
doors open is not a sign of vulnerability, but it can be exploited.
the best recommendation is to replace the doors. example, the command nmap-sF-g 53 [ip] can brular any firewall, but if the doors are exchanged, complicates the job of the striker, if he commit yet, do an audit because the attack is someone you know.
hugs