One that seems particularly vulnerable to odd problems is the system firewall.
Luckily the fix is a relatively easy one; all you have to do is remove the firewall’s preferences and then reboot the system.
I also tried all the tips I found online including disabling passive FTP and deleting com.plist and none of those seemed to work As a temporary fix I have kept that particular cable plugged into the router but I'm curious if anyone has any ideas Thanks!
For posterity, I resolved this issue by changing the order of the devices.
To reset the firewall, step-1) Go to Desktop and press command shift G step-2) Go to the /Macintosh HD/Library/Preferences/ folder step-3) Remove the file called “com.plist” step-4) Restart your computer.
For Resetting Wifi Configurations: step-1) Go to Desktop and press command shift G step-2) Go to the /Macintosh HD/Library/Preferences/System Configuration/ folder step-3) Backup and remove following files: com.apple.airport.preferences.plist com.message-tracer.plist Network Interfaces.plist preferences.plist step-4) Restart your computer. When this happens, other systems on the same network (often including similarly configured Macs) will be working just fine, indicating the problem lies with the Mac’s configuration and is not a compatibility issue with the networking hardware.Cause of the Problem: 1) System Update 2) Major Configuration changes made by users 3) System restore *4) Switched off System by holding power key When people perform major configuration changes to their systems, sometimes the settings may not migrate properly.I have tried to manually enter all IPv4 information but doesn't help To reset the firewall, go to the /Macintosh HD/Library/Preferences/ folder and remove the file called "com.plist," and then restart your computer.After the system boots, you may be prompted to allow incoming connections to numerous programs and services, so accept these for now (you can always go to the Firewall settings and deny or remove entries later on) and then try connecting to the network again.News: The Chronicle Forums will be shutting down and archived as of July 1.Our posters have created a new home: The Fora: A Higher Education Community.The PC accepts the new cable fine, the Mac tries and goes back to "Self-Assigned IP" I tried switching that particular cable attached to the Mac from coming off the Switch to coming off my Belkin router and then it works fine.Initially the Wifi didn't work either but I tried restarting the modem, router & switch and now I can get the wifi to connect but not the Ethernet.Source: Mac Rumors forums In my situation, I had unplugged the ethernet cable from my wifi router and plugged it into my Mac.My cable modem presumably didn't bridge the new MAC address, leading to the network problem. If these don't work, you might have a legitimate hardware issue.