As far as I am concerned, the WAN light should be flashing. When the internet is down, is the WAN IP address still there?

Is the powerline adapter connected to a modem or router? Now both of the laptops can be connected at the same time?

As far as I am concerned, the router supports PPPoE, Dynamic IP, Static IP etc. it seems it does not have the ability to dial up by logging into a page so that others can share the connection..

Is there an IPv4 address? if no, perhaps you can try a static IP address. what's more, How about try to change a channel on the router that may avoid some WIFI interference?

As far as I'm concerned, with the WISP mode, the security settings on the TP-LINK should match that on the main router. what's more, the IP address of the TP-LINK should be in different subnet from...

You may follow the steps below to have a try: 1. Log into the web interface of the router. 2. Select Router mode. 3. Disable the DHCP sever in DHCP Settings. 4. Go to Network →LAN to change the IP...