D-Link DSL 300 is Mac address specific!

I lost Internet connectivity over the weekend at home. My home Internet setup is quite basic – see the following diagram (courtesy of D-Link):
Home Internet setup diagram
I use my laptop almost exclusively and I have it connected to the Internet via wireless network served by my D-Link DI-624 wireless router.

On Sunday morning, my laptop didn’t register any wireless network. I thought my son had accidentally turned off the router so I went upstairs to check but no, the router was dead. Completely dead – no LED lights lighting, nothing.

No problem, I thought. I’ll bypass the router and plug my laptop directly in to the DSL modem (a D-Link DSL 300). When I did, though, I still couldn’t access the Internet!

I logged into the web interface of the modem and discovered that my ISP username and password settings appeared to be lost. Strange coincidence I thought, both devices having problems simultaneously, possible power surge of some kind? Anyway, I reconfigured the modem with the settings, downloaded my email and then connected the modem to my sons iMac so he could play.

Again though, there was no Internet access. I logged into the modem again and yet again the ISP settings were lost. Uh oh! I wondered if the modem had been damaged as well.

Then it hit me – the modem must be MAC address specific – and it was set for the MAC address of the wireless router – hence its apparent failure when the router failed. Knowing that, I left the one device connected to the modem until this morning when I had a chance to replace the wireless router.

Now that I have replaced the wireless router, all is back to normal once more (except my wallet which is a little lighter 🙁 )