If the message "MiniPLC uses an old version of RTOS V1.20, contact support" appears in the Platform Config for IPLC201 / 301, this is a misleading message, because for IPLC201 / 301 V1.20 is the latest and most current. The problem is that "despite this" it is not possible to upload a project, etc.
This is done by disabling the firewall in the OS of the computer with the IDE. Packets are blocked through the firewall and this status is erroneously evaluated as an old RTOS.