Did you contact your ISP to test the line?

Can you access internet properly? How about the internet speed when you connect directly to the main router and WA850RE?

Your WA850RE is running in latest firmware? When browsing webpages, is it working properly? Did you connect directly to your main router to test? How many signal lights on WA850RE?

Upgrade the latest firmware(TL-WA854RE(EU)_V1_140827) for your WA854RE. Reset and reconfigure it. http://www.tp-link.com/en/download/TL-WA854RE_V1.html#Firmware

WA701ND can be configured in client mode if you don't need to boost Wi-Fi signal. Or you can configure it in repeater mode if some clients need to connect to WA701ND wirelessly. How to configure...

169.254...? It is an invalid IP address. Did you try to assign a static IP on one of clients connected to that AP? What's the firmware version of it? Is it up to date? All WA901NDs have different IPs...