Network Disconnect from Cable
When there is no network, run ipconfig/ifconfig. If there is an APIPA address, then there is a clear disconnect between the device and the DHCP server.
Solutions
- Check Ethernet Cable connectivity
- Check power in DHCP server
- Check if NIC is enabled in Windows Device Manager
Link Light Connectivity
There may be a cable connection issue if the link-light does not have a stable green light and a flashing orange light. May be caused by:
- Bad port
- Bad Cable - Use a Cable Tester
- Bad Switch This is called Port Flapping
NIC Diagnostic
- Sometimes NIC driver installations come bundled with diagnostic software to check the NIC circuitry.
- Install a Loopback Plug which sees if it can receive data it sends towards itself.
Cable Testing
Using a Time-Domain Reflectometer on a cable will tell you:
- Where the cables broke
- How far a length the cable is Ensure you test with the cable unplugged from both ends and a loopback device on the opposite end
Cable Tracing
If a setup has multiple cables, that it is too hard to trace its cause, then use a toner generator and toner probe.
- Place the toner generator at one end of the cable
- When the toner probe is touching the cable with the toner generator on the other side, it will make a sound
Can’t Ping Default Gateway
- The router is down
Duplex Mismatch
The network devices configured at different duplex versions. It will cause slower network communication.