Checking the speed of the internet to the building you're working in or even at home can easily be done by running something like speedtest.net in your browser, but how do you check the speed of your local network.

iPerf or iPerf3 for Linux and Mac environments (also works on Windows), ran in Terminal is the perfect solution, all you need to two devices with it installed - one acting as a ‘server’ and a second as the client (sender/receiver) you move around and check physical hardwired connections or the wireless.

Once the package is installed, on the device acting as the server machine, plug it in to the network closest to the switch/router. (make sure you know its IP too) - ifconfig in terminal finds that.
Open a new shell window and type the below command and press enter.

This will set the terminal window in to listening mode on the port 5201

On the second machine, again open a new terminal window and type the following command again followed by enter.

This will do a series of runs to test the network speed and bandwidth and report its findings.

If you run

iperf3 -c [server ip] -R

You will get a better feel for the network speed as the test is now in reserve (server sends and client receives)

iperf will run and test in TCP mode as default, to test UDP add -u on both the server side and testing side.

Running the command iperf3 -c [server ip] -d will launch a full debug mode, as well posting the results at the end.