The PostgreSQL repository is by default configured to use IPV4. You can verify the same by checking the postgresql.conf file (located at: <<TDV Install Dir>>\repository\data\) and look for configuration "listen_addresses" in the file. You will find the configuration is defined as below:

"listen_addresses = 'localhost'" in  
or s
"listen_addresses = '127.0.0.1'"

This shows that repository is using IPV4. In order to change it to IPV6, please set it up configuration "listen_addresses" as below:

"listen_addresses = '::1'" 

Now change the below configurations for repository in TDV configuration file "server_values.xml" (located at: <<TDV Install Dir>>\conf\server\)

<common:attribute>
    <common:name>/server/config/database/connectionUrl</common:name>
    <common:type>STRING</common:type>
    <common:value>jdbc:postgresql://[::1]:9408/cisrepo</common:value>
  </common:attribute>
<common:attribute> 
 
<common:attribute>
    <common:name>/server/config/database/databaseHost</common:name>
    <common:type>STRING</common:type>
    <common:value>::1</common:value>
  </common:attribute>
<common:attribute> 

Now Restart TDV instance (TDV server, Repo & Cache). Please try to connect using studio and now TDV should be using IPV6 host/address to connect to repository. 
 

This article illustrate that how to configure TDV Repository to use IPV6.