FTP Stops when the screen auto-sleeps

[Pacomatic1]

Describe the bug
Say you're transferring a file via FTP. If I leave it to sit for a while, the phone goes to sleep.
FileZilla then says the server times out.

To Reproduce
Steps to reproduce the behaviour:

1. Start FTP Server.
2. Connect to the Server on a client of your choice.
3. Wait for the phone to go to sleep on its own.
4. Your client will say the connection has timed out/disconnected/stopped.

Expected behavior
What I expected was for the server to stay up when the phone sleeps.

Screenshots
If applicable, add screenshots to help explain your problem.

Smartphone (please complete the following information):

• Device: Oppop F9
• OS: ColorOS 7.1 running on Android 10
• Rooted: No
• Version: 3.10

Additional context
Not context but instead a suggestion: You could force the phone to stay awake while the server's up.