Can't receive any data after downloading for a long time

[zhoutingztzt]

I downloaded a large ZIP file, about 33GB, and the download time was long. At the time of download, I can't receive any data about every 30 minutes.

I used the systemctl status trojan.service command to check status of trojan service.
The service is running, and the connection with my client is also established. But can't receive any data, I can only restart trojan.service

the system is debian 9