@ArcherC8 

thanks for that. Will check firewall. 
I still couldn't find any specific settings to block unknown clients (if they had my password) from entering the network. I had that functionality with the other router. Will continue research.
 

Hickdawg wrote

On a netgear router I used to have, I could block all new  unknown clients from my network. I can only find how to block individual clients on the TP-Link router. That helps if I know who they are. If I don't, is there any way I can set up security for unknown clients?

@Hickdawg 

I'm an a V1 A20.

Easy to do. Open a Browser, Log-in to the router. Click on Advanced, then Security and then Access Control.

From that screen, you'll need to CREATE a WHITELIST. after you ENABLE ACCESS CONTROL.

You can select all the ones connected now when WHITELIST is selected and save, only they could connect. If you have some you don't want, use BACKLIST and select and save.

'Official FAQ', https://www.tp-link.com/us/support/faq/1535/

Not too clear how to ADD new devices? I suspect you'll need to turn off Access Control, allow the device in, and add it?

Using this, NO DEVICE can connect if not on the WHITELIST.