[upofadown]

... also lightning strikes hitting the ground somewhere in the area. That can induce large voltage differences between the power grounds on the buildings. The voltage difference might be large enough to arc across any isolation provided by the physical network implementation.

[kevin_thibedeau]

My neighbor's house was hit by lightning last year and it took out the ethernet ports on two of my devices. Nothing else was affected though. Those devices still work. They're on a PoE switch (though not using PoE) so that may have been part of the cause.