Router configuration troubleshooting

Published on: 26th March 2008

Making a router work properly, quickly and effectively.

by Daniel Fletcher

This is probably a highly ironic article; since if you need it's advice then you probably can't connect to the Internet!  I have installed a large number of routers for friends, family, Clients for all manner of networks.  Some of the issues concerning their configuration are very common, but rarely documented unless you know what you are looking for!  This is an article to expound on some of the more common router configuration issues.

Making a router work in the first place:

It happens all the time, the router comes out of the box, driver disks go in, but it's no go.  For most routers, I use the following method to get them running (ignoring the instructions!)

You will need:

  1. The router, powered up and connected to the phone line (ADSL)
  2. Your ISP information, username, password and protocol information
  3. An ethernet cable (we are not talking WiFi yet)
  4. A computer/laptop
You will NOT need:
  1. Any driver disks
  2. Any useless handbooks (except for 1 thing, see later)

The method:

Connect your computer to the router with an ethernet cable.

1. If you are running a PC, click start, run, then enter 'cmd'.

2. Type in 'ipconfig' and press enter. (enter ifconfig on a mac at the terminal prompt)

3. The resulting window will look something like this:




The important bit is the 'default gateway'.  If you get a blank here, then open your control panel, then network devices, and check that the IP address for your network card is set to 'assigned by DHCP' and redo step 3.

4. Open a browser window and see if you can access a site.  If you can, then you are up and running.  If not, continue.

5. Enter the address in your browser http://192.168.1.1 (or whatever the default gateway was set to above)

6. If you get prompted for a password, then enter the password as shown in the router's handbook.  If you don't have one, then do a search on google for the default password for your router model.

7. You should be able to see the router's configuration settings.  Roughly speaking the following should be checked:

Conclusion 1

If you cannot get to the router's configuration, the problem is usually on the PC/Mac end.  It may also be that the router needs a factory reset.

If you can edit the router's settings but not get online, then most of the time it is the ISP settings.  Look also at the connection with the phone line/filter installation (there needs to be 1 filter on every phone point in use on the circuit).

Finally, check the ISP protocol settings. Most connections now are on PPPoA standard (aol), some are on PPPoE with VC/MUX encapsulation.  Use a VPI of 0 and VCI 38, or 0,38 if there is a single setting.

Router optimisation

It occasionally happens that the router will work, but very slowly.  It may also be slow on some sites or even refuse some sites.  In most cases, I have found that the following can be adjusted to benefit the setup:

MTU - The MTU setting is usually defaulted to 1500.  This means 1500 bytes in a chunk may be broadcast/received at once.  This is often too much for some connections and packets will be lost causing slow/nonexistent response from some sites.  www.ebay.co.uk is a good test site that often falls over on an MTU of 1500.  Try reducing this to 1400, then increasing it gradually to the point where sites stop working so well. 

PPPoA - Sometimes an ISP will allow you to connect with PPPoE but the performance will be poor.  Try a different encapsulation method.

QoS - Sometimes a bandwidth throttle called Qos (Quality of Service) can be enabled!  Simply turn this off unless it is necessary.


Warning

Any attempt to 'improve' a router's performance will invariably cause it to fall offline at some point.  Do not attempt anything of this nature unless you have a backup system or are happy to accept that you may be offline until you fix it!  Ginzola accepts no responsibility or liability for any loss or damage caused by any router/pc/mac configurations done by anybody.