Troubleshooting internet access

Introduction

This page describes how to troubleshoot internet connection problems.

Internet access requires two things:

  1. a connection to the internet (possibly via WLAN)
  2. the ability to resolve names (i.e. to convert hostnames to IP addresses)

Complete the ‘Check’ procedures below; these may ask you to complete specific ‘Fix’ procedures below.

Procedures

Check: WLAN visibility
  1. If you are not using a wireless connection, then skip this check.
  2. Log in to the PC where you want to access the internet from and search for visible WLANs.
  3. Check the visibility of the ‘NETGEAR’ WLAN.
  4. Check the visibility of other WLANs (e.g. the neighbours’).
  5. If the ‘NETGEAR’ WLAN is visible then stop this check here.
  6. If the ‘NETGEAR’ WLAN is not visible and other WLANs are visible see ‘Fix: Resetting the Netgear router’ below.
  7. If you reach here then contact Alexis.
Check: Connectivity
  1. Start a terminal window.
  2. Run the command: 
    /sbin/ifconfig | grep G
  3. Verify that an IP address is shown; we’ll refer to this IP address as <gateway-ip-addr>.
  4. Run: 
    timeout -s 2 5 ping <gateway-ip-addr>
  5. Verify that the ping worked with 0% packet loss; if the verification failed see ‘Fix: Fixing the gateway’ below.
  6. Run: 
    timeout -s 2 5 ping 132.185.132.21
timeout -s 2 5 ping 216.239.32.10

    (These IP addresses belong to the BBC and Google respectively.)

  7. Verify that the pings worked with near to 0% packet loss.
  8. If you reach here then contact Alexis,
Check: Name resolution
  1. Start a terminal window.
  2. Run the command: 
    grep nameserver /etc/resolv.conf
  3. Verify that an IP address is shown; we’ll refer to this IP address as <nameserver-ip-addr>.
  4. Run: 
    timeout -s 2 5 ping <nameserver-ip-addr>
  5. Verify that the ping worked with 0% packet loss.
  6. Run: 
    getent hosts www.google.com
  7. Verify that an IP address is shown.
  8. If you reach here then contact Alexis,
Fix: Fixing the gateway
  1. If <gateway-ip-addr> is 192.168.1.1 then:
    1. go to the DSL router
    2. from its back face pull out the black power cable
    3. wait 10 seconds
    4. on its back face plug in the black power cable again
    5. wait 2 minutes.
Fix: Resetting the Netgear router
  1. On a PC which has a wired (i.e. not wireless) connection, start firefox.
  2. Visit http://192.168.0.10. (login is ‘admin’, password is ‘password’; these are factory defaults which have not been changed)
  3. In the blue navigation panel on the left, click ‘Diagnostics’.
  4. In the white main panel click ‘Reboot’.
  5. Dismiss the warning dialog window that appears by clicking ‘OK’.
  6. At the next page, which forces a slight delay before trying to reconnect to the router, either follow the prompts to connect to the router again or close the tab; both are fine.

See also