For the past few days I haven't been able to connect to the Internet via WiFi. I get the little error triangle over the sign, and when I go through the trouble shooting process I get a message saying that the WiFi doesn't have a valid configuration.

Typing this into Google suggests that it's a known if random issue with a Windows 10 update rather than anything to do with the router, which makes sense given that I'm typing this on my phone which is currently connected to the WiFi. However, none of the sites I've checked seem to agree on what can be done to resolve the issue, given that multiple restarts of both laptop and router have done nothing.

Any thoughts? Bearing in mind that I know basically nothing about how computers and routers work...

 

Under network connections and settings there should be a box that tells windows to automatically detect ip address make sure that's checked. Also have you done a complete restart of your computer?

 

My first instinct would be to check the IPV4 and IPV6 properties.

In the network and sharing center by clicking on the blue text next to Connections: (Should be either Ethernet or WiFi). Then a new window will open and you can click on IPV4 and make sure that both options are set to auto, and then do the same thing with IPV6.

If that doesn't work, open up the command prompt and post the results of "ipconfig /all". That will help determine where exactly the problem is coming from.

Edit: Here are some more detailed instructions for changing the IPV4/6 configuration.
https://support.microsoft.com/en-us/help/15089/windows-change-tcp-ip-settings

 

I shut it down and powered back up several times to no effect...but doing a restart seems to have fixed it. I hadn't realised there was a difference...

 

Yeah, I saw that, but it didn't seem to do anything in my case - unless restart does something different to shut down?

 

Does rebooting the modem/router help?

 

If there was an update done by windows and you had simply shut down the computer afterwards the latest update settings wouldn't configure properly. As a rule of thumb and this is for any device. Once an update has occurred you should do a reset even if your not told that it is required.

 

So yeah it was a Windows 10 update that screwed up DHCP.

http://arstechnica.com/business/2016/12/microsoft-windows-10-dhcp-broken-update/

There should be fix going out now.

Here are some suggestions to try and fix your internet to get the fix:

Open up command prompt, and type in "ipconfig /release", and hit enter.
Then enter in "ipconfig /renew" and hit enter once more. Wait a few minutes and see if the internet comes back.

If the above doesn't work, open the command prompt and enter in "netsh int ip reset", hit enter, then "ipconfig /flushnds" and reboot your computer for a temporary fix.