My colleague David posted this in our internal chat system, because we’re all working from home:

I fixed my Internet problems on my desktop the other day, my Ethernet cable was wrapped around a power lead. Apparently 230V mains causes enough EMR to disturb Ethernet.

I remember “fixing” a network issue years ago at my first IT job when I re-routed a cat-3 [sic] cable away from a powerboard cable on an office floor. The interference was so severe, it was timing out and dropping specific connections which I refuse to mention because it would age me. But it shows that even shielding and twisted pairs can be impacted.