A test authorization for monitor.packetfilters.net to the Let's Encrypt staging service has revealed issues that may prevent any certificate for this domain being issued.
Fetching http://monitor.packetfilters.net/.well-known/acme-challenge/8ZSuU0AoDEmu65uJCIPdIN9ZU2IeLnWDFPnr-f3C3wc: Timeout during connect (likely firewall problem)