NIC Disconnecting From Router Continuously

This came up frequently on the (old) Q and A that when connecting to the Internet with any application the connection from the computer Network Interface Card to the Router drops.

(Included in the router category are DSL  and Cable modems, newer models have wireless capability)

I have found over the years that when a (wired) Network Interface Card disconnects from a Switch or Router the problem 99% of the time is the parameters between the Network Interface Card and the Switch or Router are at fault.

There is a 1% chance that the NIC or the Switch/Router is physically failing or has failed and applying traffic causes the network connection to drop.

The first thing you would do is check the parameters for the NIC by opening the properties page.

For wired Network Interface Card's to a Switch (also known as an access point) you want the Speed and Duplex to be 100 Full (for a 100 MBPS) Switch or 1000 Full (for a 1GBSP) Switch.

All current wired routers for home or small business use have a connect speed of 100 MBPS and Full Duplex.

This means that if you have your Network Interface Card speed and duplex set wrong then the Network Interface Card and router will be in constant negotiation for the speed and duplex causing the appearance that the router is dropping the signal anytime the connection is made.

The only other parameter that you would be concerned with is the IP and Gateway addresses. If the router is set to give out IP addresses through DHCP (Dynamic Host Configuration Protocol) then this should not be a problem. But if you are assigning IP addresses manually insure the IP, Subnet Mask, and Gateway match the Router and the Network Interface Card (see this page: NIC for more information about IP addressing).

For Wireless your main consideration is the signal strength and any obstructions between the computer wireless Network Interface Card and the Switch / Router wireless Network Interface Card.

When you setup your wireless connection you don't have a choice on speed or duplex.

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Such as wireless 802.11 B  is 11 MBPS at full duplex, 802.11 G is 54 MBPS at full duplex, 802.11 N is 150 MBPS at full duplex. Most wireless NIC have an auto connect at what speed and duplex that is negotiated when the connection is made to the Switch or Router wireless Network Interface Card.

The wireless Network Interface Card is a radio transmitter and receiver that operate in the 2.4 GHz range. Normally only one protocol for the connection will be negotiated and it can range between the B, G, or N. When there is interference the negotiation will start at the highest protocol N and work down to B.

Note:

For Windows Wireless Users you can check the in the tray there should be an icon that looks like a computer with three curved lines radiating from the right hand side of the computer, this is the wireless Network Interface Card icon. If you place your pointer over the icon you should see a pop up that tells you the connect speed in MBPS and the signal strength.

Such as your notation is 54M Signal Strength Good or 10 M Signal Strength Poor, the first one would be akin to G and the second one would be akin to B protocol.

All electronic devices have to accept interference from other devices and must produce the least interference. What this means is that any device (wireless telephone, cell phone, etc) that transmits on the 2.4 GHz frequency your wireless devices must accept any signal that they produce and must not produce a signal strong enough to override any other device.

These devices can and will interfere with the signal. If the signal between the sending and receiving Network Interface Cards is from Good to Excellent (using the Linksys terminology) then the interference will be negligible. But if the signal is in the Fair to Poor range the interference may cause the Network Interface Card's to drop the connection.

This is one reason you can be with in line of sight and with in the radius range of the transmitter signal and still have a poor connection.

Case in point:

A customer was having problems with dropped signals from their laptop. Checking the wireless access point that was mounted in the ceiling of the office showed that the only dead spot in the office was at the desk where the customer worked. Checking around the desk I found a base telephone set that had two wireless handsets. The wireless handsets were used when the customer was away from the desk because the customer was a representative that had to be available by phone during business hours. Moving the base from behind the desk to the far corner of the desk out of line of sight for the wireless access point removed the interference the base telephone set was causing.

Problem solved.

When troubleshooting wireless problems look at all electronic devices in the area, if any are close to the computer or the wireless transmitter/receiver (access point/router/cable modem) try moving them or move the computer further away from the devices.

As with the case above moving the computer may not resolve the interference because the device may be in between the computer and the receiving Network Interface Card of the router/access point/switch, by moving the source of the interference it may lessen the effect on the computer or router/access point/switch wireless Network Interface Card.