Methods of testing server bandwidth can help you understand your server's network performance and speed. The following are some commonly used server bandwidth testing methods:

　　Speed test website: There are many online speed test websites, such as Speedtest.net, Fast.com, etc., which can measure the upstream and downstream bandwidth speed of the server. Just visit these websites and start the test and they will automatically measure and display the results.

　　iperf tool: iperf is an open source tool used to test network bandwidth. You can install the iperf server side on your server and then run the iperf client on your local machine or another remote server to measure the bandwidth speed between the two.

　　Install the iperf server on the server (Ubuntu example):

　　sudo apt-get install iperf

　　Run the iperf client on your local computer or another server:

　　iperf -c server IP address

　　wget or curl download test: Use the wget or curl command to download a large file from the Internet, and then measure the download speed. For example, you can test download speed using the following command:

　　wget -O /dev/null http://example.com/largefile

　　FTP transfer test: Use an FTP client to establish a connection with the server, and then upload or download files to measure the transfer speed. FTP software like FileZilla is great for doing this.

　　Network performance testing tools: Some dedicated network performance testing tools such as iPerf, Netperf and Nuttcp can be used for detailed performance measurement and analysis. These tools often provide more options to simulate different network traffic and conditions.

　　Please note that the results of the server bandwidth test may be affected by multiple factors, including the physical location of the server, network traffic, ISP (Internet Service Provider) performance, etc. Therefore, it is best to conduct multiple tests at different time periods to obtain more accurate bandwidth performance data. Also, note that the test may affect the server's network performance to a certain extent, so use it with caution in a production environment.