SpacemanSpiff
Known around here
Good to know, my machine will not go beyond Catalina. You can check via terminal window, if you're comfortable with command line interface (CLI).Network Utilities just got deleted in Big Sur. Looking at the apps there are a couple that would do the job.
Keep in mind, whether you look via Network utility or CLI, the speed displayed is only the negotiated speed. It is not a real-time representation of how your connection is performing.