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Slow download speeds with gigabit internet service

Posted: May 22nd, 2023, 7:03 pm
by anything6287
I'm on a gigabit internet connection which fluctuates somewhat but it always stays at 700 Mb/s which means I expect at least 80 megabytes per second when downloading on Usenet. But I never get more than 42MB/s and during the night my speeds drop to around 12MB/s.

My setup:
  • Connected using an ethernet cable.
  • Downloading to an SSD.
  • Latest version of SABnzbd.
  • Gigabit internet service.
  • Docker container running on Synology NAS (also tried Windows binary on another host)
  • Already made sure no caps have been applied.
Things I've tried that didn't solve my problem:
  • Switching downloads to an NVMe ssd instead of hard drives.
  • Used a different SSL port
  • Switched SSL cipher to AES128
  • Tried a different host on a different OS and also could not get past 40MB/s
  • Tested my internet speed on the same host using a speed test container and my speeds are around 900 megabits per second
  • Tested with a Linux ISO torrent file using a torrent client that downloads to the same download folder as SABnzbd and was able to get at least 80MB/s
  • Checked CPU and disk utilization during a download and the utilization is low.
  • Tested a different Usenet provider.
  • Tested with the test download 10GB file when you click the wrench icon.
Wrench icon test results:
  • System performance (Pystone): 461851
  • Download folder speed 1112.5 MB/s
  • Complete folder speed 1128.7 MB/s
  • Internet Bandwidth 20.8 MB/s
Obviously, the internet bandwidth result is the bottleneck. But, as I explained, my internet connection works perfectly fine. Only SABnzbd seems to have a problem. If my bandwidth really was 20.8 MB/s I would not be able to download torrents at 80MB/s or get close to gigabit speeds with a speed test container.

I don't know what else to try or even how to debug this when the application itself thinks my bandwidth is lower than it actually is.

Edit:
  • Just tested the download speed after resetting my configuration as per the freshstart wiki section and it still didn't help.
  • Tested speeds while using a VPN and nothing improved either.

Re: Slow download speeds with gigabit internet service

Posted: May 23rd, 2023, 12:27 am
by sander
> But I never get more than 42MB/s and during the night my speeds drop to around 12MB/s.

Assuming your NAS / device is not doing something special during the night, that means the cause must be something external to SABnzbd & NAS? Even something outside your local setup, so something at ISP level?

Re: Slow download speeds with gigabit internet service

Posted: May 23rd, 2023, 7:39 am
by anything6287
Maybe I should try running SABnzbd over a VPN connection to try and debug any ISP throttling...

Re: Slow download speeds with gigabit internet service

Posted: May 23rd, 2023, 8:48 am
by sander
anything6287 wrote: May 23rd, 2023, 7:39 am Maybe I should try running SABnzbd over a VPN connection to try and debug any ISP throttling...
Yes, if possible, please do so.

But if an ISP throttles, I would not expect that to be fiercer at night.

Anyway, try and report back.

Re: Slow download speeds with gigabit internet service

Posted: May 23rd, 2023, 4:58 pm
by anything6287
Here are the results for the VPN test. Thanks for your help btw.

SABnzbd internet bandwidth test before VPN

From a speedtest:
112MB/s

From the SABnzbd test:
14.3 MB/s

Speed from actual test file download (10GB):
43MB/s

Again, the actual SABnzbd download speed is different than the speed reported by the SABnzbd test. But both are lower than my actual internet bandwidth. The internet bandwidth test for SABnzbd seems pretty useless in my case.

After VPN

From a speed test:
65.33MB/s

From the SABnzbd test:
13.1MB/s

Speed from actual test file download (10GB):
24MB/s

A pretty big hit for using a VPN (even with WireGuard) but I still have the same issue. SABnzbd's download speeds under a VPN do not reach close to 60MB/s. It seems my ISP is not throttling. I guess the next step is to try NZBGet to rule out SABnzbd and report back.

Re: Slow download speeds with gigabit internet service

Posted: May 23rd, 2023, 5:05 pm
by sander
Yes, please try with NZBget.

Re: Slow download speeds with gigabit internet service

Posted: May 23rd, 2023, 9:16 pm
by anything6287
NZBget did not improve the speeds. I also tried setting different server priorities for three different providers. Plus, I tested the speeds on a third machine with my ISP router since I was using an OPNsense router. I still got the same result.

Finally, I set an equal priority to my three different providers and the speeds jumped to about 52 MB/s. But this is still half of what my internet bandwidth allows.

I'm all out of ideas. I guess 45MB/s on average is what I should expect. Although I still don't understand why SABnzbd doesn't properly tell me my true internet bandwidth.

Re: Slow download speeds with gigabit internet service

Posted: May 24th, 2023, 12:53 am
by sander
anything6287 wrote: May 23rd, 2023, 9:16 pm Although I still don't understand why SABnzbd doesn't properly tell me my true internet bandwidth.
That measurement is not perfect. We improved it with SAB 4.0.0, but still it's just an indication.

There are better tools to measure Internet speed from a system, but 1) they need external tools (like iperf3) and/or 2) they need sites other than sabnzbd.org (which might trigger questions from users / firewalls).

Re: Slow download speeds with gigabit internet service

Posted: May 24th, 2023, 7:54 am
by anything6287
I see. Well, thanks for all your help and all the quick replies!

Unless I figure something out later I'll end this by saying I bit the bullet and subscribed to a fourth provider (Frugal Usenet). I read that some people got better speeds with Frugal and at least in my case that seemed to help. My speeds are now about 65 MB/s on average and a 79 MB/s maximum. Don't know if I'll observe the nightly slow-down but so far the speeds are better.

Re: Slow download speeds with gigabit internet service

Posted: May 24th, 2023, 8:01 am
by sander
Interesting ... so keep us posted

Re: Slow download speeds with gigabit internet service

Posted: May 25th, 2023, 12:38 pm
by Puzzled
How many connections are you using for each server? Seems like you've tested almost everything. If you are using all the available connections then my last suspects are the router or the ISP. Speed test sites can give a false impression because ISPs almost always optimize those connections.

Re: Slow download speeds with gigabit internet service

Posted: May 25th, 2023, 5:55 pm
by anything6287
How many connections are you using for each server?
The maximum amount of connections. I started with 1 connection for Eweka and then tested with 5 connections, then 10, etc.. in increments of 5 until I reached 50 connections which gave me the best speeds. Then I just used 50 connections for Frugal.
If you are using all the available connections then my last suspects are the router or the ISP. Speed test sites can give a false impression because ISPs almost always optimize those connections.
I already tried two different routers including my ISP router. I did confirm I can download at 80MB/s or more using torrents so the internet speed test bandwidth doesn't seem misleading. I guess I can live with 70 MB/s instead of the >100MB/s I should normally get. Although, I do have to be more selective with providers to even get 70MB/s.

Re: Slow download speeds with gigabit internet service

Posted: August 11th, 2023, 3:46 pm
by hallamnet
Hi there.

I have the same issue running SAB in docker on a Synology 1515+ NAS.

After a DSM update rendered my SAB install useless, I installed SAB in docker and have found the download speeds have halved.

Nothing has changed physically on the network side and now seeing speeds of around 51MB compared some days using the installed version of SAB on DSM of 98MB. I am with lightspeed internet and had no issues before and now with docker, the speeds have halved.

I have tried different bridge modes and no matter what is selected, no change.

If anyone can help us out, that would be great!

Re: Slow download speeds with gigabit internet service

Posted: August 12th, 2023, 1:43 am
by safihre
Try using the SynoCommunity version, what speeds do you get?
Docker has a higher impact than people expect.

Re: Slow download speeds with gigabit internet service

Posted: August 12th, 2023, 1:57 am
by sander
Synology DiskStation DS1515+ is from 2015 (as the name implies), and has an Intel Atom C2538 (from 2013). And you were able to achieve 98 MB/s with that? Wow!

Anyway, as Safihre says: try the SynoCommunity version. Because within docker, SABnzbd achieves (gets?) less performace. Easy method to check: SABnzbd -> Wrench -> System performance (Pystone). I've seen half pystone with SAB within docker.