Thank you for your rapid response!
Yes, I did use the installer to install. That's why it went to that site when I ran go.bat.
When installing with other URLs (non 8100 port), both 443 and 80, work fine.
It could be something else on the host but I'm suspicious if maybe 443 or 80 are hard-coded somewhere (in java?).
Right now, I cannot change the Tableau Servers to run on a port other than 8100 (long story).
Thanks in advance for any ideas!
It turned out to be a strange firewall setting here on the network... Thanks!