Make sure you're using the drivers that are on the
driver’s disk that ships with the network interface card
(NIC).
Make sure the driver is loaded and the protocols are
bound. Check the Device Properties list for trouble
indicators (an "X" or "!" symbol).
Test the NIC adapter with the diagnostic utilities that
often came with the driver installation.
Check with your LAN administrator - you may need to
install additional networking software.
If
the problem persists, follow these guidelines:
Make sure the cable is installed properly.
The network cable must be securely attached at both RJ45
connections (adapter and hub). The maximum allowable
distance from adapter to hub is 100 meters. If the cable
is attached and the distance is within acceptable limits
but the problem persists, try a different cable. If
you're directly connecting two computers without a hub
or switch, use a crossover cable.
Try another network cable.
Check the LED Lights on the NIC.
Before the LEDs can be used for troubleshooting, the
network interface card (NIC) must be connected to the
network and the network driver must be installed. Most
NICs come with LEDs near the connection. The meaning of
the LED signals may be different from one manufacturer
to the other. Here is a common LED description for 3COM
10/100BT dual speed NIC. Please consult your NIC manual
for any difference.
LED | Description | Flashing | Steady (On) | Off |
10 LNK | Green: Link integrity | Reversed polarity | Good 10BT connection | No connection between NIC & hub |
100 LNK | Green: Link integrity | Reversed polarity | Good 100BT connection | No connection between NIC & hub |
ACT | Yellow: Port traffic for either speed | Network traffic present | Heavy network traffic | No traffic |
The
computer hangs when the drivers are loaded.
Change the PCI BIOS interrupt settings. See your NIC and
system manuals for more details.
If
you are using EMM386, it must be version 4.49 or newer.
Diagnostics pass, but the connection fails or errors
occur.
At
100BT, use Category 5 wiring and make sure that the
network cable is securely attached.
At
100BT, connect to a 100BT hub/switch (not 100Base-T4).
For NetWare, make sure you specify the correct frame
type in your NET.CFG file.
Make sure the duplex mode setting on the adapter matches
the setting on the switch.
The
LNK LED doesn't light.
Make sure you've loaded the network drivers.
Check all connections at the adapter and the hub/switch.
Try another port on the hub/switch.
Make sure the duplex mode setting on the adapter matches
the setting on the hub/switch.
Make sure you have the correct type of cable between the
adapter and the hub. 100Base-TX requires two pairs. Some
hubs require a crossover cable while others require a
straight-through cable.
The
ACT LED doesn't light.
Make sure you've loaded the correct network drivers.
The network may be idle. Try accessing a server.
The adapter isn't transmitting or receiving data. Try
another adapter.
Make sure you're using two-pair cable for TX wiring.
The
adapter stopped working without apparent cause.
Run the diagnostics program that came with the NIC.
Try reseating the NIC in its slot, or try a different
slot if necessary.
The network driver files may be corrupt or missing.
Remove the drivers and then reinstall them.
The
Wake on LAN (WOL) feature is not working.
Make sure the WOL cable is attached and that power is
being applied to the computer.
Check the BIOS for its WOL setting. Some computers may
need to be configured for WOL.
Make sure the network cable is fully attached to the
adapter.
Crossover cable troubleshooting tips.
When
you work with network cabling, concentrators (hubs or
switch), and NICs from different venders, it is possible
to connect everything and still have no communication
between file servers and workstations.
When there are several unknown variables, it is difficult
to determine which component is broken. Use these tips to
isolate the problem.
Determine whether your equipment complies with the
10Base-T or 100Base-TX standard.
This is particularly important for hubs and switches.
Connect a straight-through cable from the PC to the hub.
The hub performs an internal crossover so that the
signal can go from TD+ to RD+ and TD- to RD- (see How to
Make Network Cables). When you look at an RJ-45
connector from the front, pin 1 is identified on the
left-hand side when the metal contacts are facing up.
Make sure that the TD+ and TD- wires are twisted
together, and that the RD+ and RD- wires are twisted
together.
Using wires from opposing pairs can cause signals to be
lost. For a 100Base-TX cable, pins #1 and #2 , and #3
and #6 must be on the same twisted strand.
When
there is doubt whether a hub is performing correctly, or
if the impedance settings are in question, a crossover
cable can help you isolate the failing component:
Connect a file server and a client PC back to back with
a crossover cable to verify that the NIC and network
operating system are properly configured.
To
make a crossover cable, simple connect TD+ to RD+ and
TD- to RD-. The cable performs the crossover that is
usually performed by the hub. Make sure that two
twisted-pair wires are used. If the file server and
client PC function together as a small network, then
either the existing cabling or the hub is the problem.
If
there is a proper crossover, the appropriate LED comes
on. If there is a straight-through connection, the LED
does not light. A blinking LED indicates that there is a
polarity mismatch (that is, TD+ to RD- instead of TD+ to
RD+).