Hi,
Thanks for posting in Q&A platform.
How to configure hardware for NPS depends on lot of factors such as the number of users and your actual production environment, it's hard for us to recommend from forum level.
Here is a similar thread discussed before for your reference:
Sizing recommendations for NPS
Meanwhile, I would suggest you contact Microsoft Customer Support and Services where you would get a more satisfying explanation and solution to this issue. You may find phone number for your region accordingly from the following link:
https://support.microsoft.com/en-us/gp/customer-service-phone-numbers
Best Regards,
Sunny
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