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Case Study: The Offline/Online Laptop


alt: Three panels of a dog with a toy. Panel 1: 'Pls release IP address'. Panel 2: 'No release', Panel 3: 'Only hold onto expired IP'

It's not practical for home internet services to let end users distribute their own IP addresses to their devices.

The option is there, but it's far easier to let people use DHCP - You get a pool of addresses for your devices, and the router does the work in distributing them.

That way, your devices can talk to each other (Somewhat - in a L2 network, they don’t need IP addresses) and reach the internet!

But what happens when one Windows 10 device is unused for months?

The device is totally off. It holds onto an expired IP address - and then it can't get back on. That's what happened this week.

After scanning with Wireshark, no DHCP packets were being sent at all. The laptop didn't want to connect to any home internet router, of which there were two - The main one and the extender.

Flushing DHCP didn't work. Nor did resetting Winsock and the TCP/IP stack, which were new to me. Restarting didn't work either.

When you connect to a new network, it asks for the password, with the text "Or, you can hit the button on the router".

On the top of at least this Xfinity router, there is a button you can press. When a device is looking to connect, the router does all the work in sending the DHCP initiation sequence. No password required.

That forced the computer to release its expired IP address and accept a new one, saving, at the very least, about 50$ for a new extender.

The extender I use is still old and failing, but it can hold on for a moment longer.


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