I was having issue with the internet for few days on my windows 10 lenovo laptop and I followed so many suggestions and even reset the laptop but nothing worked until I found this.
The trick was to open CMD window as an administrator and run these commands and restart your computer.
c:\netsh winsock reset catalog c:\netsh int ip reset reset.log c:\ipconfig /release c:\ipconfig /renew c:\ipconfig /flushdns
That fixed the issue where my computer was connected to wifi but had a yellow triangle saying either limited connection or no internet connection. When I used windows troubleshooter it was complaining about "the default gateway is not available - not fixed"
There was no issue if I use the hotspot from mobile (iPhone) though but it's too expensive to continue using it.
Finally the solution above solved my laptop's internet issue.
UPDATE:
Above solution didn't work after next day. As wifi connection is OK, I can go to modem setup page. Here go to "Channel and SSID" and under Bandwidth select different MHz option than it's currently selected. So, I switch between 20MHz and 20/40MHz whichever works.
