…but apparently found a way to resolve this. Symptoms: after a few seconds of streaming, it is being interrupted and the client tries to reconnect, succeeds, requests next track, and the problem repeats. Logs show nothing particular, sometimes info about broken pipe only. Solution dug out in the internet, on the forums of Pine64:
ethtool -K eth0 rx off tx offWhy is that?
hardware: rockpi 4b, gigabit wired connection
From the ethtool manual:
-K --features --offload
Changes the offload parameters and other features of the specified network device. The following
feature names are built-in and others may be defined by the kernel.
rx on|off
Specifies whether RX checksumming should be enabled.
tx on|off
Specifies whether TX checksumming should be enabled.jack, thank you 
My fault I was not specific enough. I got the basics and know what that does at the execution level, my question was rather what causes it that I need to disable it for minidlna.
On the other hand, samba works perfect without disabling checksumming, and this is many more times heavier load on the interface than minidlna.