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Problems with DHCP

Before we begin most of you will be unaware that you have a problem with your DHCP, however typical symptoms are:

  1. Cannot connect to the Internet - affects PC's, mobile phones, in fact any device.
  2. The router seems to working OK
  3. Powering the router off-and-on will usually cure the problem
  4. Everything will seem fine for a few days, and then problems occurs again!

How can I tell?

You can tell when you have a problem with the DHCP functionality because your IP Address will begin with the number 169, e.g 169.x.x.x. This means your router has been unable/unwilling to provide a correct IP Address usually beginning with the number 192, e.g. 192.168.0.90

STEP1

To find what your IP Address is you need to start the command line editor by entering cmd or cmd.exe in the search field or similar. This will then display a box similar to this...

STEP2

Now type ipconfig /all at the cursor position...and then you'll see information displayed similar to that shown below...

STEP3

Now check what IP Address you've been given by your router, by checking the entry shown circled below...

The IP Address starts with '192' which is good. If it had started with '169' then you have a problem.

If it shows '169', power your router off and on, and repeat STEPS 1 thru 3 again and see if the problem has resolved itself. If it has you can carry on working just fine, although the problem could and almost certainly will occur again.

Long Term Solution

There is believed to be a problem with certain routers and their handling of their DHCP, in particular their handling of the DHCP lease setting.

If the lease is set to 'forever' rather than a particular duration, this seems to be a common denominator when these problems are seen.

To check the DHCP Lease setting for your particular router will mean logging onto it using it's IP Address and accessing its Control Panel. You will then need to find the setting within the Control Panel, and which may look similar to the Belkin Router example shown below...

 

What next?

We suggest setting the DHCP Lease Time to the largest duration available prior to the 'Forever' option. In the case of this router it would be '2 Weeks'. (see picture above)

You should then make the alteration and 'save' the router configuration, checking you've got a good Internet connection afterwards

The n you should monitor the situation to check that there's a long term improvement.