I have a Fios WiFi extender wcb6200q. Initially it worked great. Now I get very slow upload and download speeds. When I reset it, the performance improves, but in a short period of time, it regresses to very slow speeds. I unplug it, and relying solely on my main Fios WiFi router, get great speeds again. Any suggestions?
Try troubleshooting the Coax connectivity on the Extender first. To do that, connect up a device to the extender using one of the available Wired ports and remember to disable Wi-Fi on the device. If speeds remain slow while on Wired, the next step is to ensure the Coax link itself isn't out of tolerance. Log into either the Extender or the FiOS router, then look around for Status pages which indicate the speed of the coax link along with the coax link's status. If the speed is below 180Mbps (It should be 200Mbps or better), investigate whether the coax wiring or any splitters in the mix are problematic. Try different cables or MoCa certified splitters, or a different outlet all together.
If the problem is just on the Wi-Fi side of things, log into the Extender and see if playing with the channels helps any. Also, be sure that the extender is set to use WPA2 Security and that 802.11b devices are not allowed to connect.