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?
Thanks!