@pacomar88 

Thanks to remind me that the Archer VR1200v not included.

Regarding to the unstable connection issue, we can do some troubleshooting first; Meanwhile as a local customized product, it is suggested to contact the ISP to get somre help as well. 

1. Please login to the web UI of the Archer VR1200v when it lost connection and show us a full screenshot of the advanced-status page. 

2. Please go to system tools-system log to save it and send us the txt file at the same time. 

3. Who is your internet service provider and what is the bandwidth you paid for them?

4. Do you have any other old router we can use to do a comparison analysis?

Thanks in advance, and have a nice day. 

@Kevin_Z 

Thank you for your answer.

1. This is the screenshot of the advanced status page when connection was lost:

2. Below there is the screenshot of the last part of system log during the losing connection , sorry i didn't save it, but i checked, the errors was the same since about 1 am. Moreover, you can find attached the log file .txt when the connection is ON.

3. I am in Italy and i have an eVDSL contract with Telecom with a bandwith until 200 Mb/s, but in reality i have about 90 Mb/s (my home is at about 300 meters from the cabinet).

4. Sorry but at the moment i don't have a second modem for a comparison analysis. In the next day i will try to get it from someone friend.

For the moment, thank you and have a nice day!

@pacomar88 

Thanks for your reply, from the system log, we found that the router failed to get reply from the internet server, not able to dial up. 

And when the internet stops working, there is no internet IP address; from the SNR margin value, it indicates that the line quality is not very good, it is difficult  to get synchronized. 

https://www.tp-link.com/support/faq/546/

So please verify whether the DSL led is solid on at that moment;

Besides, you can use another modem router to do a comparison analysis or ask ISP to check their internet server whether it works well. 

Best regards.