At CablingPoint we get customer calls who experience unusual network disconnect and connectivity issues.
Some cabling systems may fail after in use for a long period of time . If the cabling is done properly cabling systems may last over 25 years. However depending on how the initial installation has been done and what quality cables have been used this is always not the case.
One of the common scenarios we encounter is that customers upgrade the network switches to Gigabit Ethernet and realize that some devices experience disconnect issues or reduction in network speed to 100Mbps. In most cases this happens because the cabling system they have does not support 1Gbps speeds. If you have CAT5 cables it can provide Gigabit Ethernet for short distances. But CAT 5 cable is not designed for Gigabit speeds.
In some situations network cabling issues are caused by ad hoc additions made to the cabling systems over time. Cable additions may either have poor cables or have been installed in a rush and as a result may not be properly terminated (punched down or crimped) .
Another common cause of network issues are due to switches installed in different parts of the network to get additional network connections. One issue with this approach is that it becomes extremely hard to troubleshoot network problems. Other issue is that when a switch is added to one cable drop to increase the number of connections (splitting) , the network speed is divided between the devices and you can never get the maximum network speed for the attached device.