I have a 2011 iMac 21.5" and this has been driving me nuts lately. My internet will drop using the wired connection but the LAN side works 100% fine. If I do wifi this never has happened. I do wired for higher transfer rates inside my home to my streaming devices and I have NAT's that route from external to the static IP I've assigned to the iMac. This hasn't always been an issue but has happened here and there at times. But lately it's been very persistent. I've checked all my cabling. I've used line testers and verified all pairs are valid. I've reset my router to factory settings. I have all available updates from Apple. I cleared out all my preference files and let them recreate. Nothing at all I've tried has resolved this issue. The "fix" is to either reboot the iMac, pull the wired connection and then reconnect it or bounce my router. I've had to open ssh external access to my router just so I can send a reboot command that I'm able to get back into my iMac remotely via ssh when I won't be able to gain physical access to my home environment for awhile. I booted into recovery yesterday and ran a disk repair and permissions repair hoping that'd resolve it, but did not change the symptoms. It's become a sizable pain in the rear. Does anyone have any experience with this sort of issue that can help me better pin down where the issue is?