@Riley_S Thank you for the reply.  ---  The drivers were downloaded from the download page.  The driver with the 2018 date looks to be the correct one for the T3U and the driver dated 2019 seems to be for the T3U Plus.  After installing the 2018 driver I get download speeds of nearly 120Mbps which is really close to my maximum speed on wired Ethernet.  Everything is fine until the computer is restarted ... that is when the speeds drop to approx. 50Mbps or less.  A quick look at the device manager shows that the driver is now the 2019 driver.  Windows insists on loading the incorrect driver on every restart. My automatic driver updates are disabled. It's not that a new driver is downloaded from the Internet, it is that Windows is replacing the one I install with one that it believes is correct ... but it doesn't work!  I have even gone into the group policy editor and blocked Windows auto device installation of the device IDs associated with the T3U adapter to no avail. 

One last thought. I can install my old D-Link DWA-171 adapter and it will function well with the TP-Link Wifi router.  Restarts cause no problems either.  The main difference I can see is that the D-Link adapter includes its own wifi management application and does not use Windows manager.

Re: Chipset drivers.  The instructions for that make a bold statement about using it only with the models listed.  For my adapter model it shows "T3U (Nano / Plus)".  Does this mean all three models or only the Nano and Plus models? 

Again ... thank you for the suggestions.

  @Riley_S 

I Installed the  RTL8812BU REALTEK chipset.  It worked well, with download speeds of 118 Mbps.  However, after a restart, it too was replaced by the 1030.38.712.2019 driver and was only capable of approximately 40Mbps download speeds.  You may recall that the 1030.22.202.2018 driver, which was downloaded from TP-Link website also provides nearly 120Mbps downloads which is basically equivalent to what I get with wired ethernet. I still haven't found any way of preventing Windows from loading the ".2019" driver after a restart or shutdown. I have even gone so far as to create a group policy exception after installing the ".2018" driver, which should prevent Windows from installing new drivers to the four device hardware IDs of the TP-Link adapter.  I am currently forced to use the old D-Link adapter.  It, at least, runs at about 60Mbps and has no problems with restart, etc. This adapter uses a D-Link Wifi Manager App. so the Windows Manager is ignored.

Yes I did try it on two of my other machines (one much older and another build I have just completed. It did exhibit the same behavior on those. I do not think it is a fault with the adapter, but probably what Windows believes is the correct driver for the adapter.

I'm really to the point of trashing the T3U and purchasing an equivalent D-Link adapter.

Again, thanks for your interest and concern.