CAC single sign on issues after 2020.2.6 HF2 upgrade, anyone one lese having issues and how did you resolve

Environment 2019 MPE, 2016 OS/DB 4 2019OS APEs:

SRM, SCM, NPM, NCM, Vman.

We have a multiple Orion Instance environment with an EOC over top. All  the instances dev/test and prod went fine, except one.

The errors started with the installation and a RabbitMQ 5761 error. and no ability to log in to the web.

Worked with support (She did a great job) getting me through the RabbitMQ issue.

SSO with CAC did not work. Nor did user name and password.

Working with support we blew away the web and rebuilt from scratch.

SSO with CAC did not work, but if I disabled CAC/SSO I could log on with local SolarWinds user account. So made improvements, but that does not help my userbase or the STIG score.

I compared line by line all the configurations in IIS to working environments.  They match.  web.conf matches.  IIS, Appool settings match. File folder permissions match.  STIG settings match.  Again line by line both visual and in some cases able to run a diff.  I cant count how many reboots, re-run the web configuration.  We even rebooted secondary HA DB server, failed over to that.  Rebooted the former prior in the HA group.

We ran remote packet captures with Riverbed.  But since it was same network and probably same vmhost Riverbed (as usual) was blind.

No matter what I have tried end up at the login.aspx page instead of authenticated to the users default landing page.

Any suggestion welcomed no matter how obscure or off the wall.

We have a support case they are regrouping to assist.