"RL-TCPnet is designed as a stand alone TCP/IP Operating System. This means it does not need any external RTOS or File System to run. It has an integrated tiny task scheduler that manages timeouts, events, and internal tasks." Are the tiny task scheduler preemptive?
RL-TCPnet has an own integrated scheduler and can run with or without RTX. The RL-TCPnet schedule is not preemptive and the TCPnet also does not require it.
However it also does not allow you to add further tasks.
Do you have a problem using TCPnet?