at one point in Cable & Wireless in the mid 1990's, their main network fault monitoring centre computer was a wonderful PDP-11. I didn't dare touch it, breathe near it etc. I think they were looking for a spare as it was getting slightly 'iffy'. At least there was no danger of a cyber-attack to the NOC as all my colleagues at C&W refused to believe me when I told them "the internet is coming soon" - so there wasn't any internet connectivity, as they just didn't believe in it. (I'm aware that some lucky PDP-11 maintainers will be looking after nuclear plants in the UK until around 2050)
The NOC PDP-11 running Westinghouse Brake & Signal Company Ltd software did mostly detect network problems & re-route everything via Glasgow when the WDM fibres were taken out
Oh, and whilst running the C&W network (called 'Mercury' in those days) we often tested the enormous Rolls-Royce back-up gen-set's at strategic locations. They did sometimes fail to come online & work, isn't SNAFU the appropriate acronym?