Can't Connect To Internet

I have been Googling this for about 10 hours, to no avail. Thought I'd post here in case anybody might have a thought.

We have our internet access via cable. It's been set up for about 4 years - this is not a new connection. There's a modem and a linksys Router in the mix. I have 3 wired devices and 2 wireless connections.

Last night, the cable blipped off, then back on. All of the computers had to be restarted to reconnect I guess the DNS needed refreshed or something. Problem is ... one of them won't reconnect. When I run the troubleshooter/windows network diagnostics on it, it says either "Ethernet 5 does not have a valid IP connection" or "The default gateway is not available."

This particular machine is running Windows 10.

i have started and restarted every piece of hardware lots of times. I have installed and uninstalled the drivers. I have flushed the windsock and DNS, tried using static DNS settings I found on Youtube...and I am just stumped.

I just can't get this Pc back online. Any thoughts greatly appreciated.

 

You didn't state whether the computer that won't connect is wired or wireless. We need to know that so we can offer suggestions.

 

Sorry! 10 hours - I was brain dead. the good news is that today, it's working. I downloaded and ran a tool off this site, "Tweaking.com."

I wish I knew what had caused it, because reading other people's stories makes me think the fix might not be permanent. But it is hard to fox something that isn't broken, so until it breaks again...thanks for your time!