@Biccus1 

What is the light status of the VR900 when it goes offline?

With your computer or smart phone connected to it at that time, what is the IP address and default gateway it obtained?
Note: How to get them: https://www.tp-link.com/support/faq/838/

Meanwhile, please try to access the web page and take a snapshot of the status page. 
Note: How to login to the web interface: https://www.tp-link.com/support/faq/1200/ 

Furthermore, when did you buy it?

Here is an instruction you can follow to troubleshoot as well.
https://www.tp-link.com/support/faq/2238/

Look forward to your reply.

@Biccus1 

Do you mean the internet led shows orange at that time? At that time, are you able to access internet with computer connected to it by wired cable?

Is it the screenshot of status page when the VR900 stops working? If not, please get a full screenshot of it when the internet drops out. 

Menawhile, please export the system log of the VR900.

Note: When internet drops out, login to the web UI and go to advanced-system tools-system log to save it and send it to us. 

Besides, may I know who is your internet service provider? When and where did you buy this router?

Thanks in advance, nice day.