Starting from original migration to Win 10 (last year)
Win 8 to Win 10, current version of Audacity - port audio error, solved by upgrading realtek
Did a in-line upgrade of Win 10 to solve some unrelated issues.
Port error on Audacity 2.1.2 returns. Upgrade to latest Realtek driver did not work
Loaded 2.1.3 nightly build
Audacity works again.