web development – Web application on multiple domains

I am developing a web application that will be single-tenant (one customer, one server).
/security reasons, based on customer requests, one customer has more functions than another…/

(currently web app is running only in one server)

Let’s say the main page for example: app.application.com (hosted in another server)

And is for example customer1, customer2 etc.

My idea is:
When a user logs in in the form, for example: “customer1.1234567“, I need to redirect him to his server (sub domain) for example to the address: customer1.application.com.

And this is same for mobile application, but with the difference when user login with same username (“customer1.1234567“) then request will be adressed to corresponding server in this case customer1.application.com.

Basically, the username prefix tells the system to which server the request must be addressed.

My question is: Will be there a simpler solution, or this is pretty good idea ? Any suggestion to improvement ?

I using windows server(s) ASP.net + and IIS.

Thx for any ideas :-).