Mac won't connect to internet — stuck self-assigning an IP address
A Mac completely lost internet access and started assigning itself a temporary IP address, meaning it couldn't get one from the router. Basic fixes like changing DNS, restarting, and turning off the firewall didn't help. This is a common but frustrating situation that Mac mini server users can also run into.
When a Mac 'self-assigns' an IP address, it means the router never responded with a real address, so macOS created a fake local one (in the 169.254.x.x range). That fake address only works on the local cable — it cannot reach the internet at all. Changing the DNS server to 8.8.8.8 won't fix this, because the problem is before DNS even gets involved: the Mac simply has no valid network address.
This post is a help request without a confirmed fix. Common causes are a stuck router, a bad Ethernet cable or port, or corrupted network preference files on the Mac. For anyone running a Mac mini as a server, the standard recovery steps are: restart the router first, then try a different cable or port, and if still stuck, delete the network configuration files in /Library/Preferences/SystemConfiguration/ and reboot.
Key points
- A self-assigned IP (169.254.x.x) means the Mac never got a real address from the router — not a DNS problem
- Restarting the router is the first thing to try
- Swapping the Ethernet cable rules out a hardware fault
- Deleting network preference files in /Library/Preferences/SystemConfiguration/ and rebooting often clears stubborn cases
- Changing DNS to 8.8.8.8 does nothing when the IP address itself is missing
Quick term guide
- firewall
- A security feature that controls which programs and connections are allowed through your computer's network
- Mac mini server
- A Mac mini used as an always-on computer for files, apps, backups, or automation.
- Mac mini
- A small desktop computer made by Apple.
- server
- A computer that stores files and shares them with other devices in your home.
- Ethernet
- A wired network connection using a cable.
- reference
- Using a source to find information or confirm facts while working.
- config
- Settings that tell a program how to work.
- hardware
- The physical parts of a computer that you can touch.