Sometimes a hardware issue is as simple as a cable that has gotten disconnected. It is also possible that a system or software update did not complete. If driver software is outdated it can prevent the computer's hardware from functioning. Running all available updates and restarting is a great way to begin troubleshooting and often takes care of the problem. If updates don't take care of the problem, check the connections.

Power

• Ensure power is being fully delivered from the AC plug in the wall through the power strip and from any additional power adapter into the device.
• Sometimes modular power plugs that connect to monitors, printers, and desktop computers need to be fully unplugged, then re-plugged in.
• Restart the device. In the least, it will reset all of the connected peripherals so they are all operating from the same initialization state.

Data and Signals

Follow the Signal Flow

Ensure that interconnect cables are fully plugged in along the entire course of all connections. Unplug, then re-plug each cable to be sure.

Ethernet

• Check that the Ethernet cable is fully plugged into the jack. You may need to unplug, then re-plug the connector and listen for the "click" or "snap" sound that tells you it is fully plugged in. If you pull gently on the cable near the connector, it should remain plugged in.
• Ethernet cables are relatively fragile. If they get bent or twisted too far or are run over by an office chair, for example, it can be enough to break a wire internally and ruin the cable. Be prepared to replace an Ethernet cable if there is any doubt about its physical integrity.
• The plastic connectors on the ends of Ethernet cables are prone to breaking off. Replace any Ethernet cable that has a broken tab connector on either end.
• Most Ethernet adapters and peripherals have tiny LED indicator lights to show when they are active. A yellow flashing light indicates that data are actively transmitting at speeds over 100 Mbps. Ethernet connections are typically 1000 Mbps or greater, so you should always see the yellow light when the cable is connected. A flashing green light means that the connection is good and data are transferring live.

USB

Sometimes there are too many peripherals connected to a single USB port. If this happens, some of the peripherals may not function at all, or will function erratically. If you suspect there are too many peripherals plugged into a single USB port, remove one of the USB connections and plug it into a different port to distribute the power load.

Here are references for power usage for wired USB devices. Note that there are 1000 mA (milliamperes) in 1A (1 amp).

• A mouse can use as much as 100 mA.
• A keyboard can use as much as 500 mA.
• A web camera can draw as much as 500 mA.
• USB 2.0 ports deliver 500 - 900 mA.
• USB 3.0 ports deliver up to 900 mA.
• USB Type C ports deliver up to 3A (3000 milliamperes).
• A USB multi-adapter should only ever be plugged into a single USB port, due to the larger power requirements to support all of the potential connections on the adapter.
• USB hubs or adapters that provide more USB ports do not provide more power and are still limited by the maximum power delivery available on a single port. A powered USB hub has a separate power connector and will not draw power from the computer.

Simplify

When things don't work, try to simplify the number of active connections. Remove all connections, then add and test one at a time, until you identify what specifically is causing the problem.