In this situation when Red LED is blinking on tplink extender or red light on tplink extender you can go through the easy troubleshooting steps to fix red light flashing on tplink extender.
Make sure your tplink extender is connected to a power supply source and receive a proper power supply
If red light on tplink extender it could due to no or poor internet connectivity.
Red LED blinking on tplink extender may be due to outdated or corrupted version tplinkrepeater.net firmware software.
If the above steps fail, you can reboot your tplink extender.
Need assistance you can easily get in