Slow download speeds on Synology

[mrp8278]

I'm running Sab 4.1.0 via Docker (linuxserver dot io image) on a DS920+ (DSM 7.2) and my download speed via my provider (newsdemon) caps at 40MB using 50 connections. My internet connection is 800Mb down/20Mb up and I've tested Sab on my Windows PC which is wired to the same network switch as my DS and I can fully saturate my internet connection so I know it's not a limitation of my provider. I've combed through every forum and reddit post I can find, and also reviewed all the settings mentioned in the SAB "high speed download" troubleshooting guide but nothing moves the needle. When I run a speedtest from my DS itself using the ookla speedtest tool (executed via ssh on the DS itself) I am getting close to 900Mb on my download speed so I know the DS can handle it. Curiously, when I stack up multiple usenet servers I can fully saturate my internet connection my DS Sab install, hitting around 100MB/s - this is using 50 connections on newsdemon, and 50 connections on usenet.farm. Usenet.farm on it's own is able to hit better speeds than newsdemon, with just that provider I'm able to get up to 70MB. Combining them both and I can easily and consistently max my internet connection. I had been thinking my DS hardware was somehow the bottleneck but because I can achieve full throughput using multiple providers at once on the same hardware, I'm having trouble understanding how there could be a hardware/resource issue with my DS.

Here are all of my detailed specs:

Synology Diskstation DS920+
DSM 7.2
8GB RAM
4x WD Red 8TB (SHR)
2x Samsung EVO 970 NVME 512gb (RAID1) read/write cache
Dual 1Gb NIC with link aggregation enabled

Primary provider: newsdemon
50 connections
SSL enabled, port 80

SAB wrench status report (from SAB 4.1.0 Docker container on DS920+)
Used cache: 0B
System Load: 0.34 | 0.31 | 0.22 | V=169M R=91M
System Performance (Pystone) 165911 Intel(R) Celeron(R) J4125 CPU @ 2.00 Ghz
Download folder speed 179 MB/s /incomplete-downloads
Complete folder speed 173 MB/s /downloads
Internet Bandwidth 39.8 MB/s 318.4 Mbps


What I've tried so far, none of which has had any impact and in some cases even reduced speed:
-Reduced number of connections/try different numbers of connections- 50 yields the highest speeds for me
-Broke LACP/LAG on DS and tested using single 1GB NIC
-Tested different provider ports for both encrypted/unencrypted
-Set cipher to AES128
-Disabled encryption completely
-Disable direct unpack
-Enable pause downloading during post processing
-Set processing on default folder category to "download"
-Increase receive_threads
-set download_sleep_time to lower values including 0
-Reduce article cache limit from 1G to 500M
-Reinstall docker container
-Install brand new docker container with fresh settings
-Install native SAB packet from synocommunity (no difference in performance than the docker image)
-Rebuild NVME drives as RAID1 volume (unsupported on DS920+ but performed manually via SSH), establish incomplete and download folders on new volume - tested under both docker and native package and also no difference in speeds
-Tested nzbget synocommunity package - no difference in speed
-Tested splitting newsdemon account connections across different servers (uswest, news, nl, us, eu)
-Enabled/disabled jumbo frames on DS (normally I leave MTU set to 1500)

I don't really want to sign up for multiple providers. Since my Windows PC can cap out my internet connection on a single server (newsdemon with encryption enabled, 50 connections) it seems it's not my provider. Is there anything else I'm missing?

[safihre]

Hmmm, you have tried everything I would have suggested..
It's probably something about how fast the underlying OS handles connections that we can't do much about.
Since both nzbget and the SynoCommunity version of Sabnzbd have the same speed.

[sander]

Curiously, when I stack up multiple usenet servers I can fully saturate my internet connection my DS Sab install, hitting around 100MB/s - this is using 50 connections on newsdemon, and 50 connections on usenet.farm. Usenet.farm on it's own is able to hit better speeds than newsdemon, with just that provider I'm able to get up to 70MB. Combining them both and I can easily and consistently max my internet connection. I had been thinking my DS hardware was somehow the bottleneck but because I can achieve full throughput using multiple providers at once on the same hardware, I'm having trouble understanding how there could be a hardware/resource issue with my DS.

Interesting. I can think of only one hypothesis: your Synology Celeron can handle only X MB/s per connection, with X something around 1 MB/s

Could that explain your experience on Synology and PC (with your PC a higher MB/s per connection, for example 2 or 5 MB/s)?

A test would be to find & use one provider that allows 100 connections. I believe eweka does that (but eweka is in EU, so no max speed if you're on another continent)

[mrp8278]

Thanks for your comments, looking at eweka it seems they only offer 50 connections max. I'll see if they have any deals coming next month for black friday.

[safihre]

Yeah but like sander says, you should be in EU for it to work. Otherwise the overhead of connecting to another continent will make it much slower.

[mrp8278]

I'm not in EU but I actually get better speeds on usenet.farm than newsdemon on my DS so a EU based provider may not necessarily be negative in my particular case.