Hello @Syouak 

Thank you for reaching out to us and welcome to the TP-Link community.

Can I know the brand and model of the host router that the WR820N connects to? When building a WDS you should bare in mind that:

"In order to build a successful WDS connection between different devices, it requires that both devices use the same wireless MAC address format. For example, Site A uses 4-address MAC Address format in passive WDS bridge mode, Site B also uses 4-address MAC Address format in active WDS bridge mode.

WDS may be incompatible between different products (even occasionally from the same vendor) since the IEEE 802.11-1999 standard does not define how to construct any such implementations or how stations interact to arrange for exchanging frames of this format.-----From Wikipedia"

You can try to change the wireless channel on the host router and find a less congested one, then connect and configure the WR820N again to monitor if it connects stably.

@Syouak 

Thank you very much for getting back with the detailed info.

Can I have the model number of the ASUS ADSL router that the WR820N is extending? When the WR820N stops working, will it connect back if you restart both the ASUS ADSL router and the WR820N but do not reset it?

BTW, where is the WR820N located? Please place it between your ASUS ADSL router and the Wi-Fi dead zone, you can also try to relocate it and monitor the connectivity.

Are there any special settings on the ASUS ADSL router that may disconnect the WR820N from the network? How about other wireless devices, are they connecting to the ASUS ADSL router fine?