Hello, what is the current light status?

After initial setup, the default IP has changed, not 192.168.0.254 anymore, it is suggested to login to the web UI of main router to get the current IP address of RE450 and use it  to login. 

Regarding to the unstable connection issue, how far away between the extender and main router？ Have you setup different wifi name for it? 

Besides, it is suggested to troubleshoot and narrow down the root cause as below instruction: https://www.tp-link.com/en/faq-2233.html

Meanwhile, we need get some details: like the light status, the stability of the wired connection, whether you can get internet from the main router when RE450 stops working?What is the IP/default gateway you obtained at that time and so on. 

Have a nice day. 

Hi Layla,

All leds on means that the RE450 should be working fine, after setup, the default IP address won't be 192.168.0.254 anymore, instead, it is assigned by the main router. 

It is suggested to find the current IP address of the RE450 on the web UI of main router and then you can use it to login.

You can take some time to test, any updates, just let us know.