Didn't try this before. Why not connect the AV500 behind the airport extreme to extend the range?

Do you mean the wireless name of the plugs or the model number? The model number can be found on both the device and packaging. If you install them one by one, the wireless name of the plugs will not...

Is the server directly connected to the router and working with internet? Make sure the sever get the normal IP address from the router.

which mode did you use？ You can try another mode, such as repeater mode or hotspot router mode. Mac clone seems to only work for wireless router mode.

You can contact TP-Link support to see if they can duplicate your issue and find a solution for you.

Good sharing! For the parental control settings, I think you can send a feedback to TP-Link support and ask them to modify this in the future.