Network performance issues on macOS, not Linux

Hello

I have three machines running Serviio:
Mini: An old Mac mini Server (i7 4C, 16GB RAM)
Hack: A newer Hackintosh (i7 20C, 128GB RAM)
Debian: An old AMD (Ryzen 1700 8C, 32 GB RAM)

All machines are connected to the same network via their built-in gigabit ethernet adapters. All run Serviio.

I've noticed that when streaming larger files (e.g. UHD BD remuxes) from either of the macOS machines, the built-in player on my LG OLED will stutter continuously, to varying degrees. If I use Kodi on the TV (I've rooted it), it will also stutter, though not as frequently, but worse (larger buffer, I assume).

When streaming from the Debian box, I don't experience stutters.

Today, I decided to troubleshoot this. I've put the same UHD BD remux locally on all three machines, and playback stutters when streaming from both macOS machines. The Debian machine streams without stuttering.

I thought the Debian box might be using jumbo MTU frames, so I enabled that on both macOS machines. No difference. After checking the Debian box, I realize it's actually running the default 1500-byte MTU. Ironically, while both macOS machines had nothing else accessing the drives from which they were streaming the remux, the Debian machine had full-throttle reading (verifying checksums on copied dataset) and full-throttle writing (mirroring from USB-attached external movies drive) going on on the same drive it was streaming the remux from without a single hiccup.

I then tried mounting the MKV from the Mini box on the Debian box and streaming it from the Debian box' Serviio instance. Like so:

Movie folder on Mini (stutters when streamed from Mini directly) exported as a network share
+--> Mounted on the Debian machine using SMB/CIFS.
+--> Added to the Debian machine's Serviio Library
+--> Streamed using Debian's Serviio instance.

Result: No stuttering. So, the EXACT same file will stutter when streamed directly from Mini, but stream flawlessly when instead shared to a different machine on the same network via Samba, and then served via Serviio from that box.

I don't know of a better way to rule out general network issues than that. Something is "wrong" with the way Serviio streams files on macOS that is "right" with how it streams on Linux.

But what? Any ideas?

Cheers

PS: I just remembered: Not so long ago, I was troubleshooting this just on the Hack box. I created a 100-GB RAM drive and copied a UHD BD remux onto it to see if serving directly from memory would get rid of stuttering. It didn't.

I thought the Debian box might be using jumbo MTU frames, so I enabled that on both macOS machines. No difference. After checking the Debian box, I realize it's actually running the default 1500-byte MTU. Ironically, while both macOS machines had nothing else accessing the drives from which they were streaming the remux, the Debian machine had full-throttle reading (verifying checksums on copied dataset level devil) and full-throttle writing (mirroring from USB-attached external movies drive) going on on the same drive it was streaming the remux from without a single hiccup.

I then tried mounting the MKV from the Mini box on the Debian box and streaming it from the Debian box' Serviio instance. Like so:

Movie folder on Mini (stutters when streamed from Mini directly) exported as a network share
+--> Mounted on the Debian machine using SMB/CIFS.
+--> Added to the Debian machine's Serviio Library
+--> Streamed using Debian's Serviio instance.

If your current drive is formatted as APFS, try moving the test file to a drive formatted as HFS+ (Mac OS Extended). APFS has complex metadata and space sharing features that, in some configurations, can cause spikes in latency during sequential reads, while HFS+ is simpler and sometimes faster when streaming large sequential media.

If your current drive is formatted as APFS, try moving the test file to a drive formatted as HFS+ (Mac OS Extended). APFS has complex metadata and space sharing features that, in some configurations, can cause spikes in latency during sequential reads, while HFS+ is simpler and sometimes faster when streaming large sequential media.

Thanks But it's not, though — all drives are HFS+ except one, that's ZFS. Also, like I mentioned, if I mount the drives that the movies are on on the Debian box, Serviio streams files from there perfectly from the Debian box. I.e., there are no problems reading files on the Mac-based machines.

But cheers Happy Sunday!