Hi,
The certificate installed on the ACI Simulator Sandbox (https://sandboxapicdc.cisco.com/) is not the correct one. The certificate presented when browsing to the APIC has no SAN (Subject Alternative Name) configured, and the Common Name is configured as “devnetsbx-netacad-apicem-1.cisco.com”, which is a URL that points to an APIC-EM (i.e. something else entirely). The certificate configured on the Simulator needs to be changed.
I would also highlight that the certificate must have the identities (hostname/FQDN etc.) that will be used to connect to it in the SAN field. The use of Common Name in browsers as part of the certificate identity checks has been deprecated for some time now, so failure to specify a SAN will cause browsers to throw cert warnings. See https://textslashplain.com/2017/03/10/chrome-deprecates-subject-cn-matching/
Cheers, Lee