CRM 2016 On-premise : All organizations redirecting to Default Organization

Hello,

I am using Microsoft Dynamics CRM 2016 On-premise and below is the scenario - 

1. There are 3 Organizations created on the CRM box.
   1. DefaultOrg = Default Organization set for all the users
   2. OrgA  
   3. OrgB
   4. OrgC
2. Deployment Manager > Select Microsoft Dynamics CRM > Action > Properties -
3. Web Application Server = DefaultOrg.mycrm.mydomain.in
4. All other CRM services are set to DefaultOrg.mycrm.mydomain.in
5. HTTPS is enabled and IFD is also set.
6. IFD web URLs to access all above Organizations working perfectly.

Problem :

When I type : https://DefaultOrg.mycrm.mydomain.in --> Redirects to Default Organization as it is set for all the users.

When I type : https://DefaultOrg.mycrm.mydomain.in/OrgA --> Working fine and redirects to correct Organization.

But, When I type : https://OrgA.mycrm.mydomain.in/  --> Redirects to Default Organization DefaultOrg. ----> It should display OrgA Organization.

Can anyone please help me what should I do to get last URL working? Do I need to configure anything on IIS side?

Thank you,