Whole afternoon went on a report that the new site would not load for one person in an office of six. Same network, same browser version, same everything. Traceroute fine, dns fine, other sites fine.
Her machine had a free zonealarm firewall install from about 2011 on it, still running, with a rule set nobody had opened in a decade. It was silently dropping connections to the new ip after the host move, becuase the old ip was in an allow list and the new one was not.
tl;dr the site was never down, one desktop had opinions, and I now ask what security software is on the machine before
Source: r/WebsiteHealth · by /u/mikkel_karlsson