Thursday, March 04, 2010

Network Cable DIsconnected...

Sounds like a very simple problem right? Well, it took me an hour to fix and the solution is so simple but it's never the first thing that comes into mind.

So yesterday I came home and Joey was asking my why Youtube upload keep failing, and upon inspection, the network connection was down. Here are the steps that was taken in sequence.

  • Check LAN connection on router - connection was intact
  • Check LAN connection on PC - connection was intact
  • Unplug LAN cable from PC and plug into my MacBook - MacBook detected LAN working - therefore PC LAN port fried?
  • Plug cable as peer from PC to MacBook - no problem, APIPA assigned and can ping each other (after turning off firewall at Windows 7)
  • Both LAN ports on PC and MacBooks seems OK. Router issue? Tried all 4 ports from Linksys WRT54G to PC - no connection - no lights at all and Windows says that Media Disconnected
  • Tried all 4 ports from Linksys to MacBook - all ports working!
  • Took out my 8 port 10BaseT hub and connect to Linksys - no problem - lights on
  • Plug my MacBook into 10BaseT hub - obtained DHCP and able to browse Internet
  • Plug PC into 10BaseT hub - lights we on but no DHCP IP
  • Restarted DHCP Client service - no help
  • Disabled NIC and reenable - no help
  • Uninstall NIC driver and reinstall - no help
  • Rebooted PC - numerous time - no help
  • Changed the NIC card auto-negotiation setting to both 100Mbps and 10Mbps - no help
At this point - you must be wondering that it's a hardware issue - well it's kinda. The solution is ... <drum roll> ...

  • YANK the power cord from the PSU, wait for a few seconds to make sure all power is discharged - and turn PC back on. Everything works fine now.
Conclusion? I think it's a combination of a few things:
  • The house had a power trip that evening,
  • It was never an issue before coz I had a UPS
  • The UPS died last year
  • Somehow the NIC card thinks that the Linksys caused the power trip and therefore actively rejects it - until a complete power cycle (from the mains power, that is) is performed