Is there any way to disable built-in connection pool? (Driver for .NET)

I am not good at english, so the sentences may not be fluent.
As mentioned in the title, I want to disable the built-in connection pool. Is there any way to do this?

The use of scenarios are as follows.
I want to implement a connection pool middleware, which can manage connections of multiple type data sources, such as some relational databases, redis and mongo etc. The pool size works for database instance by ip and port. Distributed applications access data sources through this middleware. In this way, i can control the total number of connections for all programs.

I try to set MaxConnectionPoolSize = 1 and then create multiple MongoClient instances. But, Docs say multiple MongoClient instances created with the same settings will utilize the same connection pools underneath. So it seems not a right way.

Looking forward to your suggestions, thanks.