@sasan2026 

Hi, 
In your situation, you can try the following steps:
  1. Ensure your router's firmware is up to date. If not, update the firmware and check if it helps.
  2. You can refer to the following instructions to troubleshoot: TP-Link LTE Router keeps disconnecting
 

Please provide more details if the same phenomenon persists.
  1. What's the Archer MR200's hardware and firmware version? You can log in to the router's web UI and go to Advanced > System Tools > Firmware Upgrade to see the version info.
      How to log in to the web management page of TP-Link 5G/4G Router
  2. Is the router connected to a SIM card or a modem/router to go to the internet?
  3. When the issue occurs, what's the LED status on the router? Are your client devices connected to the router's Wi-Fi but have no internet connection? Please send us a screenshot of the router's web UI > Advanced > Status page.

Best Regards