Hello @Archer1800 

Can I know who is your ISP?

Please try the following procedures to ensure you've configured the AX1800 to connect to the internet successfully:

1. Power off both the ISP modem and the AX1800;

2. Wait for 5 minutes;

3. Power on the ISP modem;

4. Wait for 5 minutes;

5. Power on the AX1800 and connect it to the ISP modem LAN port;

6. Wait another 5 minutes, then check if the LED will turn green.

If still no internet on the AX1800, but the internet still works fine when connecting the PC directly to the modem, please try to clone the MAC address of the PC to the AX1800 as follows, then check the internet again:

How do I configure MAC Address Clone on my TP-Link Archer Router? (Situation 1)