Enable Server

certutil -setreg policy\EditFlags +EDITF_ATTRIBUTESUBJECTALTNAME2

net stop certsvc
net start certsvc

Steps

• Go to https://you-ca/certsrv
• Request for web server certificate
• Paste in your certificate signing request
• In the additional attributes, use the following syntax

SAN:DNS=<Name1>[&DNS=<name2>...][&IPAddress=<IP1>...]

Resource

Adding Subject Alternate Name (SAN) into Additional Attributes (encryptionconsulting.com)

windows server 2008 r2 – Subject Alternative Name not added to certificate – Server Fault