Metallic ethernet is explicitly not designed to be used between separate buildings so you really should not use it for that application. The physical layer can

Metallic ethernet is explicitly not designed to be used between separate buildings so you really should not use it for that application. The physical layer can survive surprising overvoltage conditions, but it is insufficient for lightning strikes and there is no sane way to add surge protection at the building entry as would be done for telco outside plant copper wiring.