Always check the patch cables!
I was recently assigned to look into reported connection issues and slowness of a database application for a particular user at a client, and spent close to an hour working through standard troubleshooting procedures trying to isolate the cause. After working through all of the usual configuration issues, I began checking the physical connections, and found the PC was connected through a 5-port 10/100 switch. I first replaced the switch, followed by replacing the existing Cat5 patch cables with new Cat6 patch cables. Due to the system having been forced to navigate it’s network connection through the 10-year-old switch and 12-year-old patch cables, the PC had auto-configured the network connection to 10/100 half-duplex – after changing the settings to auto detect, the system connected at gigabit speeds with no performance issues – problem solved!
While it’s common to plan for the rotational replacement of PCs, laptops, and servers, many times cabling and convenience switches will remain in place until problems like these surface. Regularly replacing small items like cables and convenience switches may seem silly, but as found above, they can cause all kinds of issues, and for a few dollars, it can save headaches and time!