What does "flap" mean here? I don't quite understand...
"If the LAN connection is absent, the connection gets disconnected." Did you refer to wireless connection?

Flapping means that the connection intermittently get connected and disconnected repeatedly.
And once the LAN connnection is disconnected from computer LAN port, the wireless connection gets reset and I have to repeat the re-configuring process

I would contact TP-LINK technical support directly if I had a similar problem because it is so weird... Your device is acting abnormal...