No connection "media disconnected"

[monton]

I have a desktop with an integrated Realtek PCIe GBE Family Controller NIC.
I use a BEC router and a gigabit Netgear switch
All has been well with wireless and wired connections including my TV, ROKU3, 2 laptops, 2 phones, and to tablets on the network.
A few days ago my desktop lost it's connection (wired) it seems after an update of Avast Pro Anti virus. Maybe coincidental.
In device manager I found an exclamation mark for the NIC.
I downloaded the latest driver from ASUS, (Motherboard P8Z77-VLK) for the NIC and installed it. The exclamation mark is gone and device manager states the device is working properly. No connectivity.
With cursor over network icon = Not Connected - No connections are available
Unplugged both router and switch and rebooted. Ipconfig states media disconnected. Moved cable around to no avail. Unplugged from desktop and plugged into laptop. Works fine. Replaced cable with same results. Plugged straight into router with same results.
I have tried ipconfig /release and renew but media disconnected. Reset winsock, ipv4 and 6
Windows firewall reports Private networks not connected. Guest or public networks connected. I don't know what to do next. While no errors are reported in device manager I think the NIC may have failed or something is amiss with settings/software. Any suggestion would be greatly appreciated. Thanks all! BTW Windows 10

 

[bazz2004]

Perhaps check out your theory as regards Avast Pro AV by uninstalling it. Windows Defender and the Windows firewall do a decent job and there are plenty of freeware AV solutions including Avira Free to choose from. Free and simple has a lot to recommend it when it comes to security software.

 

[monton]

I have had Avast Pro for awhile. I've never had a problem with it and upgraded when they had a sale for 9.95. That has been over a year but this most recent program update may have precipitated the problem. Also, the lights on the NIC are both out, no blinking. It is worth a shot to uninstall Avast. Will that return the settings to pre install/defaults?
Thanks for responding, I appreciate the help and suggestions. I live in Vermont so I won't be working on the computer for awhile. I'll be shoveling snow for the next several hours. Sigh

 

[DelJo63]

Screenshot shows Not Allowed, meaning you can only do this from an Admin account OR
runas /user:administrator cmd
and run inside the new window.

 

[monton]

I noticed that the lights on the onboard NIC were out, no flashing. Device manager said it was working correctly. I purchased a Rosewell 10/100/1000 PCI NIC ($7.99) and installed it. Started computer and got a black screen. This was reported in the customer reviews. I rebooted and everything was normal. W10, apparently, loaded drivers. Using the original cable I was up and running w/o further problems. Wanted to share the resolution.
Thanks jobeard and all the great folks on techspot for your help and support