Question Download speed doesn't equate to my actual bandwidth determined by speedtest ?

beta2k

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My download currently maxes out at 3mbyte/sec. I have a connection that is capable of 150mbit/sec download. I confirmed this by doing a speedtest:



However, when I download something from an FTP server or try a test-download from some test server, the speed always maxes out at 3mbyte/sec.



However, this should be higher, because 150 megabits/sec bandwidth should amount to something like 18 Megabytes/sec download speed (or maybe a little bit less if you subtract some overhead).

I already moved from wifi to an ethernet connection, to no avail. I disabled my firewall and real time antivirus. I used different ethernet-cables and different LAN-ports on the backside of my modem.

I don't know what limits my download speed. And I dont understand why the speedtest shows much higher speed. I am also quite sure that it has nothing to do with network card drivers since the issue appears for both the WiFi and the Ethernet connetions.

Two things that I can only try tomorrow when I am back home:
  • try to download with a bootable linux version
  • try to download with a different laptop
Any help is really appreciated.
 
It can be the download server or its location that is likely different from speedtest. If you choose speedtest servers in different cities or countries you will see very large variations in the results.

I would try a download from some other location using a different method. Maybe try microsoft and download a large windows install image. You could also try one of the game company downloaders like steam. Steam like speedtest and stuff like torrent is using a multi session transfer to increase the speed. This tends to help when the latency is high.

FTP tends to not be very fast it also is not secure and when you add in a encryption tunnel it makes it a bit slower. Not sure about the site you tested with the web browser could just be that site.

The only thing on your end it could be is if there is some issue with the disk subsystem since speedtest does not store the file. This is very unlikely.

You can do very little about slowness because of distance to the server or other issues in the network. It could be some setting in the FTP client, I have not used FTP in years because of complexity of running it securely
 

faalin

Illustrious
Lets look at your internet speeds just as an example

150mbps down 32mbps up
or
18MB/s down and 4MB/s up


If i was to request a file off your computer the fastest i could get it is 4MB/s because thats your upload speed. So depending on what server your requesting info from, by their upload speed, and how many people are requesting at the same time will limit how fast you can get the info.

Our work has a 1gbps + download speed but only a 50mbps upload, at 50mbps or 6.25MB/s we limit our FTP site to 3MB/s Just because you have a fast download speed does not mean thats what your going to download at, it all dependent on the other servers upload speed.
 

beta2k

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But how do you explain that I got much faster speeds from the same server a few days ago? I tried in the middle of the night (1am) and very early in the morning (7am). Congested traffic should not be the issue. And I talk about servers who have synchronous up/down speeds.

For instance, I am trying to download from my own FTP server which is geographically in a country close by. The server has a gigabit connection. I copied files from my FTP to google drive with 30mbyte/sec via rClone. So I am certain that I should get the same speed. Actually not the same, because I dont have a 30mbyte/sec connection. But I'd certainly expect more than 3mbyte/sec.
 

geofelt

Titan
There are two components; communication time from the server and the time to write the data to a drive.
What kind of a drive are you writing to?
You may be limited in writing data once the data device buffers get full.
 

beta2k

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I just confirmed that I have the same slow speed at my friend's connection where I had much faster speeds the last time. The download is still stuck at 3mbyte/sec no matter what I download from which server.

I am starting to think that the limit here may be my local drive or the connection to my drive? But how can this be? And why does it appear suddenly? I am using a Samsung SSD 860 EVO 1TB.

Update: This is the health status of my SSD. Looks good right?

 
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PsychoPsyops

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You have to think of the speedtest as the benchmark that it is. It is meant to push it to the max to show you your top available speed possible, rather than a constant speed or average.
There are many different variables that can affect speed as well and it is usually determined by the server and it's location.
 

DSzymborski

Titan
Moderator
Benchmarking download speeds by individual server downloads is a poor method unless can verify being able to download from the same site from the same place on another device at a faster speed.

Also, make sure to keep megabits and megabytes separate since they're not the same thing.
 

beta2k

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unless can verify being able to download from the same site from the same place on another device at a faster speed.
this is exactly what I did.

same internet connection, same download, different laptop: the download reaches the full bandwidth of the internet connection at about 12mbyte/second (compared to the 3mbyte/sec on my laptop).
 
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beta2k

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Another interesting thing I just realized: When I download something from google drive, I get full speed.



I also tried with a virtual linux machine. still slow speed from FTP and another test file via HTTPS. The HTTPS was fast from my friend's laptop (on the same connection). so it cant be the server.
 

beta2k

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Problem solved. I had to do the following command in an elevated cmd terminal:
netsh int tcp set global autotuninglevel=normal

apparently, a few days ago, i set this to another setting in an attempt to solve the slow download speed. but back then I actually didnt have the issue, but maybe was facing slow speeds due to congested wlan. so making that wrong setting made thins worse... and i reverted it now and (on cable) i have full speed now.
 

DSzymborski

Titan
Moderator
Problem solved. I had to do the following command in an elevated cmd terminal:
netsh int tcp set global autotuninglevel=normal

apparently, a few days ago, i set this to another setting in an attempt to solve the slow download speed. but back then I actually didnt have the issue, but maybe was facing slow speeds due to congested wlan. so making that wrong setting made thins worse... and i reverted it now and (on cable) i have full speed now.
Well, hopefully it stays like this! Free solutions are the best kind.
 

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