@Kevin_Z same problem with AV600, just bought yesterday. 

Adapters connect ok, the utility is showing both.

I can ping the router from the computer connected to the second adapter, and I can ping the computer from other computers (connected directly onto the router and via wifi).

I connected one of the other computers on the powerline, and it too didn't have any access on the internet.

The computer that is connected to the tp link powerline can not access anything on the internet.

The gateway and dns server addresses were unknown, I had to manually enter my LAN's information on the computer connected to the powerline to get the positive ping results.

Any ideas? Thank you in advance

@Kathy_Z hi! same problem with a av600, via wifi isn't a powerline.

The ip with the wi-fi directly to the router and with ethernet on the av600 isn't the same. How can I solve it?

I changed manually the ip on the av600 settings, searching the ip on chrome. That doesn't work. I need a solution now pelease.

THANKS IF U CAN HELP. :(

@calvaax 

same proplem with my AV600. It was working fine for a few weeks, no changes lf any kind happened and it stopped working. All the LED lights are exactly where they should be, the app says the device is working fine, it shows as being conected to the network but whenever i conect a device to the extender i cannot acces the internet with that device. 
The main router it's connected to works fine as well as all the devices (laptops, phones) that try to connect to it. There was no change in router or anything so I don't understand why it stopped working. 
This is very frustrating as the device is relatively new, and we were not expecting this for the price we paid for it. 

@BaasB. 

 As a first step, open a command promt on your computer. Ping 8.8.8.8. then ping www.bbc.co.uk.

If the first one gets replies and the second doesn't, then it's a DNS issue. If this is the case, change the DNS server to 8.8.8.8.

@Kathy_Z 

I had a similar problem, just bought the AV600  TL-WPA4220kit and had success pairing the adapters. The ethernet cable was working in the living room where the router is located, but as soon as i take the adapter to my room and connect the ethernet cable to my pc it says that there is no access to internet. The pairing green light is not so bright anymore and occasionally lights on and off. Can you please help me? Is the problem the outlet i am plugging the adapter to? If so, how do i fix it?

@William_Wu 

The extender needs to be plugged into the wall socket. Is this the case or is it plugged into an extension?

@Kathy_Z hi i am currently using TP-Link WPA4220 Powerline (using wifi connection)

All the lights on my adapter and extender is working fine but i can't seem to connect to the internet.

It happens only intermittently. After I turn on and off, I could use it for a few mins and it is back to "No Internet"

Tried to reset multiple times. Still the same issue.

Appreciate if you can help me! Thank you.

@Kathy_Z followed your instructions and got it to work thankfully, using the app helped also to manually synchronize the IP addresses on the extender and the main router

Kathy_Z wrote

@calvaax 

Good day.

Thank you very much for your time and patience.

May I know the model number of your main router?

You already checked the IP address, especially the default gateway are not from the main router, right?

Can I have a picture of the different IP parameters when connected to the router and powerline adapter?

And they are two suggestions that you could have a try:

1. Reset the power-line adapter by holding the reset button/pinhole on the AV600 Wi-Fi extender for 10s; then pair it again;
2. Log in to the web interface of the power-line extender; then manually turn off DHCP;

(As for the subnet mask, gateway, and DNS, you could refer to the related settings on the router.)

Thank you very much!

, as I was struggling to open up a webpage on any device so I would suggest anyone still struggling to install that first before any of the other steps, thanks for your help!