I found that with a 3 attenna router, leaving the middle one vertical and the other 2 horizontally out gives the best performance. Any thoughts, anyone.

Just and observation and you may want to confirm this. Speedtest results consistently poorer using Chrome versus Internet Explorer, despite using the same speedtest client and location.... In my case as much as 100Mbps.
Speed is highest when the client application is used directly, e.g. Use speedtest.net application either android or Windows