miniDLNA (ReadyMedia) disconnects after few minutes

I’m using miniDLNA on my Pi 3 and I’m encountering weird issues that I’ve never encountered before, after setting up the Pi from scratch.

Setup

• Pi connected via internal WiFi and via ethernet
• DLNA via miniDLNA on NTFS-mount (also accessible via Samba)
  • listening solely on the ethernet adapter (eth0)

Problem

The smartTV, which I’m using to watch video files, is disconnected from the DLNA device a few minutes after playback has been started.
At least, this is what the TV tells me.

There’s no warning or related info message in the miniDLNA-log.

However, on rare occasions the connection is stable and allows to play for 30+ minutes.

Probably Networking Problem

Sometimes SSH loses the connection at these exact moments as well but I’m not quite sure if this may be due to the SSHD option ClientAliveInterval.
If I try to SSH into the Pi immediately again I often get:

ssh: Could not resolve hostname pi3: No address associated with hostname

which resolves automatically after a few seconds.

There’s no information about possible causes in syslog. I solely get notified about established SSH sessions and there’s literally no output between intermediate logins after such a disconnect:

Feb 21 22:27:20 pi3 systemd[1]: Started Session c67 of user sebschlicht.
Feb 21 22:34:08 pi3 systemd[1]: Started Session c68 of user sebschlicht.

Quintessence

My DLNA and probably the whole Pi is occasionally disconnected and sometimes remains unreachable via hostname for few seconds, rendering my DLNA service practically unusable.

What is causing DLNA to disconnect? May it be a random network disconnect? If yes, how to debug that situation? Do you have any idea what may cause it?

I’d appreciate any help.