Slow download speed despite fast connection

[zuus]

Hi there, I've been trying to figure this issue out for a while with no luck so figured I'll try here.

Despite my gigabit internet connection I cannot get a sustained speed in sab faster than around 10MB/s. It starts off around 20MB/s then over about 30 seconds drops to under 10:



I've asked others in my country who use the same ISP and they get a sustained ~80MB/s using the same newsgroup server so it's not an ISP throttling issue. I have tried routing sab through a VPN just to be sure and it gets exactly the same speeds. Have also tried lowering the number of connections to the newsgroups server which only further decreases the speed.

I have a server running OpenMediaVault (Debian) with an i7 9700T, 32GB RAM and using a 2TB SSD for sab's complete/incomplete processing folders. Sab is running in a docker container, but I have tried setting it to use the host network and also tried running it directly in the OS (not in docker) with the same result.

Performance figures:


One other variable is the router, my current being an Asus GT-AX6000 running MerlinWRT. Everything else including bittorrent downloads at full speed (110MB/s), it's unfortunately only newsgroups that's having this issue. QoS in the router is disabled and it's using full HW flow control. It's connected to the server via a 2.5Gbit link and iperf3 shows hitting full speed between the server and my main PC has no issues there.

Has anyone using AsusWRT/MerlinWRT had any issues with sab? Unfortunately I don't have a different router to test with at the moment but if others do have issues with Asus I'll consider getting one.

[sander]

Thorough analysis ... nice!

You leave out of thing: your own location. Which I (as admin) could see. Others from your area have complained too.

Let's try some more iperf3 stuff:

iperf3 -R -p 5207 -P20 -t30 -4 --format m -c ams.speedtest.clouvider.net

... what are the last lines?

Oh: "Debian server". Do you also have a pc/mac where you can run SABnzbd on?

[zuus]

You're right, I missed that detail! It's Australia.
I do indeed have an Arch (btw) main rig that is a 5800X3D/32GB/4TB NVME. I've installed sab on that (not in docker) and attempted a download with the following results:

Performance:


Weird download behaviour:


As for iperf3, this is the result (grepped for the last lines):

It definitely shows very similar behaviour to what sab is doing.

[sander]

So with iperf3, with 20 connection to AMS (aka Amsterdam), the speeds drops to below 100 Mbps.

I think you have to solve (or accept) that.