Hello,

I am sorry but the TLCP version is not customizable because it is a requirement about the capabilities of the Lightstreamer Server which are needed by the plugin.

However the source code of the Flutter plugin is open source, so you can try to loose the requirements but only to some degree.
For example you can force the Flutter plugin, which depends on the Lightstreamer Swift Client SDK, to use the Swift Client 5.0.0-beta.4 instead of the version 5.0.0, which is the last released one. In that case the TLCP version requested is 2.3.0, which is a little better than 2.4.0 but still far from 2.1.0.