How to fix RealTek "Sleep Mode" error

I don’t know what is going wrong with RealTek Network Adapter of my Gigabyte Z68MA-D2H-B3 Rev 1.3 Motherboard. I keep getting the below error message even when I have installed latest driver for it.
"The RealTek Network Adapter/Controller was not found. If Deep Sleep Mode enabled Please Plug the Cable"
I have tried uninstalling and reinstalling driver for it several times but I can see if in Device Manager neither I am able to get it work. Is there anything I can do about it? Can this be an issue with the board? I have bought this board recently and I don’t think there should be any issue with it but I am not that sure about the same.

It appears as if there is something wrong with your RealTek Network Adapter but it can be because of bios as well. You should first try clearing cmos and if that ends your issue then its well and good but if that doesn’t then update your bios to the latest and load it to default. You can download latest bios for your board from Gigabyte official site. Just make sure that you are updating it to the latest available. If you don’t get any help from these things then you will have to get your board repaired or replaced. I don’t think there is anything else that you can try out for fixing this issue from your end.

I wanted to know if you have checked out your bios for settings like "Enable On-Board LAN" or similar. I think you might have not enabled it in your bios. So if there is a setting for enabling it in bios then you can use that, if you don’t see anything as such then as Kanesteyn as suggested you will have to get your board checked from its service center. As RealTek Network Adapter is an Onboard Adapter you should not try messing with it. If you want then you can try using a 3rd party PCIe-card-based NIC temporarily.

Even I think the same now, I mean I have tried out clearing cmos, updating bios, restarting my computer several times, uninstalling and reinstalling latest driver for it but no matter what I am not able to get it working. Everything worked fine for 2 weeks after installing Gigabyte Z68MA-D2H along with its driver but I don’t know what went wrong with it suddenly. I am not willing to invest in getting a 3rd party PCIe-card-based NIC, rather I will go for rma.

You can try disabling sleep mode for Network Adapter and check out if that’s making any difference. For disabling sleep mode for Network Adapter you can follow below simple steps:
Go to Control Panel> System and Security > Device Manager >Expand Network Adapters > Properties > Power Management Tab > Uncheck “Allow the computer to turn off this device to save power”