Finally achieved 600Mbps download on Ookla speedtest.net through Balance One; 767/174 Mbps was the high after multiple tests on multiple servers. The key was using the Edge browser (Win 10) instead of Chrome, configuring speedtest.net to Single Connection instead of Multi Connection, and I did not log into the Balance One (the Dashboard display uses CPU). Selecting Single Connection severely limits the upload speeds for some unknown reason. Upload speeds increased to a high of 567Mbps on one of the Multi Connection tests.
Thanks to @soylentgreen, @rossh_pl_beta and @zegor_mjol for your responses which helped guide me to this resolution.
