There are a great deal of factors that can affect upload and download speeds from a dedicated server.
Resource usage: This is typically the most common culprit. Heavy CPU, RAM, or I/O usage can severely limit the transfer speeds that the server is capable of. The easiest way to diagnose this issue is to test within a clean environment, such as a Linux Live CD.
Peering and Congestion: Specific routes may have points of congestion, where the full throughput speed is not available at a specific point along the route between the server and client. Our direct connections with our upstream are guaranteed never to be more than 80% utilized, to allow for traffic bursts.
Distance: The further the distance between the client and the server the points of congestion and the higher the latency. Both of these can have a major part in transfer speeds. If there is no congestion along the route, the server OS may not have TCP Windows Scaling enabled.
In Linux, you can perform the following command to test speeds:
iPerf3:
curl -sL yabs.sh | bash -s -- -g -f
Speedtest.net (Ubuntu/Debian)
sudo apt-get install curl
curl -s https://packagecloud.io/install/repositories/ookla/speedtest-cli/script.deb.sh | sudo bash
sudo apt-get install speedtest
Speedtest.net (CentOS/Redhat/Alma/Rocky)
curl -s https://packagecloud.io/install/repositories/ookla/speedtest-cli/script.rpm.sh | sudo bash
sudo yum install speedtest
Miami: speedtest -s 12215
Los Angeles: speedtest -s 19230
New York City Metro: speedtest -s 18956
Article ID: 194, Created: February 22, 2015 at 11:27 AM, Modified: February 10 at 1:35 PM