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LAN failure

I came home to a seemingly fine PC today. This was not the case: First off I couldn’t look at this site. Second, google.com wouldn’t load. Third, I had no LAN connection.

Odd. Checking my switch, I saw that there were no lights at all. For some reason I suspected the power supply so I swapped it for a spare (I collect stuff like this). That seemed to do the trick and I had lights all over the thing. Still no LAN connection on my PC, though. There were lights on my PC’s LAN port, but they weren’t blinking. The corresponding lights on the switch weren’t even on. I pulled switch out of things and tried hooking up my old WRT54G router - that wouldn’t talk to my pc or the rest of the LAN.

To check my sanity I started hooking the WAN port on the router to other ports. All the LAN ports seem fine, and I connected to the switch and that seemed fine. My PC’s LAN port is dead though and, by the look of things, so is the house’s switch. Figuring this out, I got out a little usb wifi dongle and at least got online.

A little later I noticed the switch was off again. Unplugging it I felt how hot it was - it’s a NETGEAR gs108 with an all metal case - it normally runs quite cool. I plugged it in again and all the lights seemed to blink. I checked the ports again and noted that port 8 (where the upstream switch connected) and port 3 (where my PC was connected) were not functional.

At this point I should point out that today I experienced the closest lightning strike I can recall. I was in my office looking towards the windows, when they suddenly lit up with an immediate accompanying bang. This may explain the above situation.

So my PC is miraculously fine other than the dead LAN port, but I can buy a PCI LAN card to fix that and wifi will suffice for now. The switch seems to have some electrical fault and looking inside I saw a fairly healthy looking power section, one giant QFP IC under a huge (and hot) heatsink, and an array of FM-3178LLF components. I can’t find a datasheet for these, but the bi-tek site has this product page. So these are the magnetics for the ports - maybe the IC is alright but one of the magnetics infront has shorted and can be cut off. I’ll have to get a multimeter or scope to check this out - I’ll update when I do.

I’ll also have to give the IT service desk a call.

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