That’s kind of vague so I’ll take a wild guess of: Maybe it was rewired incorrectly? Of course there are many possibilities here. For example, maybe the rewiring involved a tech visit, and maybe the tech replaced, or updated, or changed some settings in the router?
Was the wire that was cut electrical or optical? For example, I could imagine cutting a DSL or cable line sending a spike to some connected equipment. (Although it doesn’t seem likely.) I’m assuming such a thing couldn’t happen with fiber optic.
Banned but back. Because why not?