Method 1: Power Cycle Modem and Router
TP-Link Wifi Modem can connect and work with most Modem types but in some cases we will need to perform the "Power Cycle" operation to be able to establish the connection. Please try:

Step 1: Turn off the Modem and Router for about 1 minute

Step 2: Power on the Modem device first and wait for about 2 minutes until the cable is stable and receives the light signal of the internet light.

Step 3: Turn on the TP-Link Router again.

Step 4: Wait for 1-2 minutes and then check the internet access to see if it is okay. And if you've done all the steps above and still can't fix the TP-Link wifi modem error, try the 2nd way below.

Please note that device Power Cycle is essential every time you try one fix

Method 2: Change WAN connection type to Dynamic IP
Before proceeding with TP-Link Router installation, if your computer device can access the network without running any other programs, please use Dynamic IP for WAN connection type. Then T-Link will use Dynamic IP mode automatically. If you did not change the previous settings, you can completely stop this step and move on to another method. The detailed way is as follows:

Step 1: Open a web browser and enter the router's LAN IP address and the default will be 192.168.1.1 or 192.168.0.1 and press Enter.

Step 2: Enter the Username and Password to proceed to login (all admin will be for both)

Note:

If you get a message saying server error -401, that means the Username and Password information is incorrect. If you have forgotten the information, you will need to reset the router to factory defaults.
If you don't see the login page when logging in, you will need to refer to the reason why you cannot log into the TP-Link wireless router's utility management page to check. This article will guide you to the following:
Step 3: Select Network-> WAN in the menu on the left, then change the WAN Connection type to Dynamic IP and then click Save to save the settings.

Step 4: After that, wait a few minutes and then proceed to check WAN part on the Status page. If you see the IP address display (similar to the image below), it means that the connection between the Router and the Modem has been established.

Step 5: If your IP address is still 0.0.0.0, try retrying the previous TP-Link Power Cycle wifi modem error or follow it by “Clone the MAC address”.