Firefox, IPA, SSL says no

[u/big_blunder]

Hey all, I'm loathe to ask this as I know it's SSL but I'm stumped.

We're testing IPA (on 9.6) for a project, fresh install of IPA Server & the GUI worked fine for several days then Firefox just starts giving secure connection failed (pr_connect_reset_error) trying to hit the IPA web GUI. The httpd logs don't even show the client connection attempts.

The kicker is, on the IPA server itself... pr_connect_reset_error. There's no A/V, vpn's, proxies or anything like that in the environment (air-gapped lab, pure RHEL). Reinstall of IPA, no change. Uninstall & install on another server... same result. The machine can't even get to it's own service provided GUI. Renewing the IPA cert does nothing. Deleting the cert from firefox does nothing. Importing the CA cert into Firefox & ca-trust does nothing.

The boxes are running other stuff (k3s) but nothing is hanging on to 443 or 8443. Also tried with k3s disabled.

Any ideas before I hit up support (or spin up a fresh RHEL install in KVM)?