@omar1234 

Hello, thanks for posting on TP-Link Community.

1. Were you using the same AV600 powerline units with your old WiFi router? and were they working fine before in the same house?

2. When you connect to the powerline extender WiFi now, will it just reboot once and then stay stable, or in a reboot loop until you disconnect the WiFi?

3. What is the brand and model no. of your new router? and what is your network topology such as how each devices are connected to each other?

4. Does the issue happen when a specific client device connects the WiFi? or it happens when any device connects?

5. The router WiFi still works fine or not when the powerline units plugged in? 

6. Please try different wall sockets to plug in the powerline units to see if it makes any difference.