The TLS certificate was created with the CN:
but the only way I am able to get to Vantage web client is by using the AltName.
If I use the CN name instead, I get the following message: NET::ERR_CERT_COMMON_NAME_INVALID
Nowadays the browsers do not trust the CN field alone. They trust the SAN (Subject Alternative Name) extension.
If you want to use multiple names (for the multiple urls to use) then you should define both of them as SANs in the TLS certificate. Please refer to the doc "What is a Multi-Domain (SAN) certificate?" for additional information.