Main router: PLDT Home Prepaid Wifi Advances (BoostEven) Cat-6.
The extender is updated to the newest firmware version and is placed near the router.
I tried to configure the extender in 3 ways: web, WPS, and Tether app, but neither of them works. It connects to the router for about 3 seconds and disconnects ang repeats.
I finnaly found a way, by connect the RE with router using wired LAN and disconnect the LAN, then the WAN works. The success connection rate was about 2% and I have to reconfigure ang do all the work once the extender has turned off.