@Sharper9 

I would use the set up that involves using your web browser or Tether. If you try to use the WPS setup it will add "_ext" at the end.

Here is how you would use Tether to set up the extender: https://www.tp-link.com/us/support/faq/1373/

Here is how you would use a web browser to set up the extender: https://www.tp-link.com/us/support/faq/1400/

I used Tether and the iPhone saw the extender. I renamed both 2.4 and 5.0 and it connects. Then later it comes up with 'No internet connection' in orange on the iPhone/iPad Wi-Fi. . But then they will not connect with 'No internet connection'. If you use an extended wifi link after the first connection you get you then get 'No internet connection'. It is driving me mad.

@Sharper9 

After the RE300 is set up, look at the 2.4G and 5G LED lights on the extender, both should be on and the signal light (wave icon) should be white. If that is not the case the password being used during the setup may be incorrect.

If all lights are lit normally, check your router settings to see if anything could be blocking the internet to the range extender. Possibly reaching out to the router maker to see if there may be any settings that can block an internet connection.