Instead of visiting sites like Speedtest.net through a browser, you can install speedtest-cli package on Linux and test bandwidth speeds from the command line.
$ apt-get install speedtest-cli
Here’s an example running the command.
rich@kreinix:~$ speedtest-cli
Retrieving speedtest.net configuration...
Testing from DQE Communications LLC (63.133.254.190)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by Magna5 (Boyers, PA) [73.79 km]: 10.854 ms
Testing download speed................................................................................
Download: 771.21 Mbit/s
Testing upload speed......................................................................................................
Upload: 820.98 Mbit/s