@Johnshin111 

Hello, do you mean that the Deco network is unstable, you lose the internet connection frequently, right?

We need do some troubleshooting first to locate the issue so that we can try to fix it later. 

1. What is the current network diagram? And what is the model number of your Deco?
2. What is the led status of the Deco when you lost connection? How do you make it back to work after that?

3. At that time, with computer connected to the main Deco directly, can you access internet? Try to simplify the network diagram, in other word, connect the main Deco to the modem only and then connect your computer to the main Deco to verify whether it works well.

4. If still the same, please connect the computer to the modem, bypass the main Deco to test whether the network works. 
5. Besides, you can try to relocate them and swap the locations of Deco units.

Thanks in advance, and have a nice day.