Can I change the internal nerdio.int domain?

The nerdio.int domain can certainly be changed -- but only when first creating your account.

To do so, you would use the advanced option on the provisioning screen that appears after you have clicked "Add NFA Account".

We recommend something customer-specific, followed by .cloud. It should not be a name that is too similar or identical to anything that is already in production.

Unfortunately once an account has been provisioned the internal domain cannot be changed.