The oddest part is I can set the Mac to static and it acts like it's online (gets notifications from nearby iPhone, such as messages, apps, handoff works, etc, and update notifications come in, apps sorta work) but any attempt to open a site in Safari ends with 'you're not connected to the internet'
Terminal, try to ping yourself works. Ping 8.8.8.8 or the actual gateway results in 'host not reachable' or 'no route to host'
Using DHCP, it doesn't even wait. It instantly just defaults to 169.254 IPs. Same for any iPhone, iPad. Reboot router doesn't fix it. Windows PCs like my Windows 11 laptop and Windows 7 desktop have no issue getting a DHCP address from the same network router. Just Apple and that one Windows 10 PC fail. I spent hours yesterday troubleshooting without success. Tried even using different wireless NICs and a USB adapter for the Mac, no dice. Same issue.
The Windows 10 PC only works being connected via ethernet. The oddest part is this particular router won't let me get in via a static IP. At home, my router allows internet access even without the DHCP server if I set a static IP if I run out of leases, but this one is an oddball. It's an AT&T Uverse DSL router/modem from the year 2008, so it's probably on its way out anyway. I can however open its setup page via the Windows 11 laptop and it shows no errors, nothing out of the ordinary in the logs, and plenty of DHCP leases available. Even the MAC address of the Mac shows, but lists itself as 'inactive'. Any attempt to dig farther into the 'meat' of the router settings is blocked by AT&T of course.
I once had an instance at my mother's house where her DSL modem died. I tried to go to all sorts of stores; Best Buy, Walmart, Office Depot, even Kmart (when they existed) and they all told me that DSL is obsolete, and no one makes the modems anymore. That was in 2011. I am not sure how true that is, but mom ended up going with a cable modem, and work remains on this quiet old DSL system. Work is out in the middle of nowhere so only DSL and satellite is an option. With this bug however it's gonna be, well, interesting. Can't get a new modem/router and can't separate it by using a new router with modem in modem only mode because AT&T blocks the settings from being available to the user. Calling AT&T is met with their horrible customer service saying 'you still got Uverse?!' as if it were something right out of the 1980s or something.