Hi vince_intel, I changed the Gigabit Master Slave Mode setting to "Force Slave Mode" and then rebooted, but the link speed is still only 100 Mbps.
I also posted this issue on the Linksys forum. There, I was asked to plug in to each of the four ports on my router and report the link speed. After posting that all four connect at only 100 Mbps, I was told the router is defective. However, it seems odd that two other laptops connect to the ports on the router at 1 Gigabit, if the router is defective. Obviously, the problem exists only with the combination of my 82579LM and Linksys WRT 1900AC, but how do I know which one is the root problem?
Hi sean-TX, further isolation can be done by trying out the 82579LM on other gigabit router or can you share the network adapter brand\model on other laptops that was able to connect at 1 Gigabit, let's try to find the difference between 82579LM and those NICs. Another angle to look into is compatibility issue between the NIC and gigabit router.