@C.L
Hello, thanks for posting issue on the community. As for the disconnect issue, please confirm some basic info, then we will try to fix it:
1. May I know who is your ISP? Please ensure the modem is always stable first.
2. What is the light status of the C4000 when the connection drops out? Can you get internet from it via wired cable at that time? Please connect your device to the modem directly to do a comparison test as well.
3. When the network stops working, please check the IP address and default gateway with your computer connected to the modem/router separately and show me the status-details page. Instruction as below:
https://www.tp-link.com/support/faq/838/
At that time, please login to the web UI of the Archer C4000 and take a full screenshot of the Advanced-status page, and go to Advanced-System Tools-System Log to save and export it to us.
Besides, please follow the instruction below to do some test and tell me which case you belong to.
https://www.tp-link.com/support/faq/2237/