Tag Archives: connection

Troubleshoot a Slow Computer Network – Only One Computer on the Network is Slow

Only One Computer on the Network is Slow

Client Computer Network Mask Wrongly Configured
Your network is a class C network, (net-mask 255.255.255.0), and your client computer has its IP address configuration on a class B network, (255.255.0.0). Change the network mask of the client to match the network configuration.

Poor network cards
Bad network cards or bad drivers are very often the reason for poor transfer rates. Test the transfer rate with a different network card.
An outdated computer can also slow down your network transfer.

Bad Network Configuration
DNS Configuration
can be the cause a of slow network connections.
Wrong DNS address in the IP configuration can slow your network dramatically. Your DNS client will try to connect to an inexistent or not working DNS server then give up and try your secondary DNS server. This translates in slowdowns and sometimes even DNS resolution errors.
Fix: Ping the DNS address or, even better, use nslookup and connect to both of your DNS servers to check if they work.

The TCP/IP protocol stack corrupted.

Sometimes no matter what you do you can’t fix the network and this is because the TCP/IP becomes corrupted. The only thing that fixes it is a reset. On older Operating Systems, such as Windows 98 and Windows NT, the fix was to uninstall and reinstall the whole TCP/IP suite of protocols.
Fix: issue the following command to reset it: netsh int ip reset c:\resetlog.txt.

More Than One Default Route
Advanced Lan SettingsA very common mistake is to assign more than on default route to the same computer. Do not confuse load balancing with multiple Default Gateways. You are configuring two network cards, and both of them have a default gateway. This configuration will not work. Usually, a Windows computer will warn you that this is not a good idea, but some users will choose to ignore the warning.
This is a typical problem for laptop users, they connect into the Lan environment and leave the wireless connection on. This will create a lot of problems for corporate users and even for home users.
In order for this type of configuration to work, special routing rules and IP configuration is needed. it is easier to turn the wireless of or have an adapter manager that will automatically do that for you based on your rules.
Advanced Tcp/IP Settings
On a Windows XP there is a way to assign priorities to network cards using a graphic interface. from the Network Connections applet in the Control Panel, click on the Advanced menu and choose Advanced Settings.
On the Advanced Settings window arrange the network cards according to the correct priority.
Another way to achieve this is to change the gateway’s metric for each of the network adapters on the computer. To do this, open the TCP/IP properties on each of the network addapters with a default gateway configured, and click on the Advanced button. On the Advanced TCP/IP Settings window, uncheck the Automatic Metric for the Default Gateway, and enter a value according to your network topology. The lower the metric, the higher the preference for a default route.

This article is part of a five posts series regarding Network Troubleshooting.

Computer Network – Tools and Supplies

Punch down tool

Punch down tool – The punch tool is used to insert the network cable in the patch panel or similar connection panels. For a small network up to 7 devices you might not need it as you can easily connect all of your devices directly into the switch.

Keystone module RJ45

Keystone Jacks – The RJ45 keystone jack is the female connector, usually immobile, part of a network connection that is mounted on the wall or similar. It provides a network connection close to the device to be connected. A patch-cord is used to connect the device to the keystone jack.

There are many types of RJ45 keystones, some require a punch down tool to be used, and some are tool-les, providing a lever for insertion and a retaining clip to secure the connection. The keystone is also produced for various categories, (Cat 3 – Cat 7), make sure you buy the correct one.


Deep Surplus
Wire Stripper Twisted Pair Cable

Wire stripper / Knife – I am not a fan of the wire stripper because it always cuts a little of the wires. Most of the times, the cut is superficial and it doesn’t get to the wire. But sometimes the stripper will scratch the wires. Using a utility knife or cutting pliers, is a little more laborious but I prefer it as I get more control. Moreover the many crimper tools come with a cable stripper. Don’t use that one, it doesn’t work for round cables, it only works for flat cables.

Simple Cable Tester

Network Tester – This is not a must, but if you are doing this for the first time, it will save you a lot of troubleshooting. For professional network cabling an expensive Network Tool that can measure attenuation, cable length, category supported, etc…, it’s a must. You need to give your client a report with your measurement results.
For small DIY jobs a simple tester will do it.


Patch Panel

Patch Panel – This is beyond the purpose of this article since it applies to bigger networks.

Network Switch

Network Switching device – The switching device switches packets between the different devices on your network. Modern switching devices can make a virtual map of all of the devices in your network and route packets according to this map.

Older connectivity devices, such as network hubs, used to indiscriminately broadcast the packets on all of the ports and only the device which the packet belonged to would have accepted it. This design creates a lot of collisions and saturates the network with unnecessary traffic.

Network hubs, (two or more ports), or repeaters, (only one port), are used to increase the maximum of 100m, (333 ft), between two devices connected on an Ethernet segment. Every repeater adds up another 100m.