Invalid (network stream) driver mode
A driver mode was set that the current network stream driver does not support. For example, a TLS-encryption mode may have been set for the plain tcp (non-TLS) stream driver.
Note that ordering of statements is important: if e.g. you select TLS driver mode on line 1, but select the TLS driver on line 2, that will fail. If you swap lines one and two (thus specifying the driver before the mode), the sequence will work.