Obviously, wired connections made by ethernet cables are more reliable, stable, and interruptions-free than wireless ones. This is because there is physical connectivity and hence the possibility of losing the connections and latency is low. So, as you do the Linksys re6500 setup, try to attach your extender to the router using an ethernet wire. That will help you to achieve a hassle-free and successful setup. Once you are done with this, also connect your device to the extender using the ethernet wires. But, make sure to use the box-included and original wires while attaching the devices together. These are more capable of better signal transmission due to their superiority. However, to keep the connection strong and safe, check those ethernet wires and ports on a periodic basis. You also must replace the wires after using the older ones for a long time.