IT/Software/Command Line Applications/iperf3
General
Install
sudo apt install iperf3
Usage
Server
This is the computer that will listen for requests for speed checks.
On the server you need to start listening
iperf3 -s
Server Options
-1 is great as it allows for one check from a remote client and then exits the program
Client
This is the computer that will try to dial into the server to test their communication speed
On the client you need to send the request
iperf3 -c ipAddressOfServer
NOTE: If the server is on a dynamic ip and or behind a router that does not have the port forwarded then you will need zerotier setup to get to the listening computer.
Client Options
-V tell you more
-t 5 will only check five times. Usually enough