After upgrading to gigabit broadband, the speed was still only 100 Mbps. Testing revealed that the Linksys router was limiting the device's speed. By adjusting the priority settings and turning off the speed limit feature, the speed increased to over 800 Mbps. The problem stemmed from the router misjudging the external network speed, which caused the bandwidth between devices to be limited. After the correct configuration, network performance returned to normal.