DNS_PROBE_FINISHED_NXDOMAIN on almost every site

if every device in the house gets it, log into the router and look at its DNS settings. if there's a server there you don't recognise, someone (or some malware) changed it. put it back to automatic or a known one, then change the router admin password too, a lot of people still have the default printed on the sticker. if it's only one PC and the flush didn't help, look at the hosts file in Windows\System32\drivers\etc. anything listed there overrides DNS.

that error means your computer can't look the site names up, so it's DNS, not the sites. does it happen on your phone on the same wifi too? if yes, restart the router. if it's only the computer, open command prompt as admin and run ipconfig /flushdns, then netsh winsock reset, and reboot. still broken after that, change the DNS server on your network adapter to 1.1.1.1 or 8.8.8.8 instead of the ISP's. and if you've got a VPN or a security suite with web protection, turn it off for a minute to test, those break DNS more often than you'd think.