If timeoutMS is set, drivers MUST use min(serverSelectionTimeoutMS, remaining timeoutMS), referred to as computedServerSelectionTimeout as the timeout for server selection and connection checkout. The server selection loop MUST fail with a timeout error once the timeout expires.

After a server has been selected, drivers MUST use the remaining computedServerSelectionTimeout value as the timeout for connection checkout. If a new connection is required, min(connectTimeoutMS, remaining computedServerSelectionTimeout) MUST be used as the timeout for TCP socket establishment. Any network requests required to create or authenticate a connection (e.g. HTTP requests to OCSP responders) MUST use min(operationTimeout, remaining computedServerSelectionTimeout) as a timeout, where operationTimeout is the specified default timeout for the network request. If there is no specified default, these operations MUST use the remaining computedServerSelectionTimeout value. All commands sent during the connection’s handshake MUST use the remaining computedServerSelectionTimeout as their timeoutMS value. Handshake commands MUST also set timeouts per the Command Execution section.

If timeoutMS is not set and support for waitQueueTimeoutMS has not been removed, drivers MUST continue to exhibit the existing timeout behavior by honoring serverSelectionTimeoutMS for server selection and waitQueueTimeoutMS for connection checkout. If a new connection is required, drivers MUST use connectTimeoutMS as the timeout for socket establishment and socketTimeoutMS as the socket timeout for all handshake commands.

See serverSelectionTimeoutMS is not deprecated and connectTimeoutMS is not deprecated.