Monitor_port and rfc2217

I am using the TelnetStream library to stream debug info from a ESP8266. It works fine receiving the data on a telnet terminal on an Mac.

Now I would like to receive the same data in the Platform IO IDE using the settings in the platform.ini file:
monitor_port = rfc2217://IP-adr.local:23

However when opening the Monitor in the Platform IO IDE I get the error:
could not open port 'rfc2217://IP-adr.local:23 Remote does not seem to support RFC2217 or BINARY mode [we-BINARY:False(INACTIVE), we-RFC2217:False(REQUESTED)].

Any ideas what the problem is?

When I scroll through the RFC it talks about negotation packets and configuration commands etc on the protocol layer. On the other hand, the

Is just a TCP server and client. It’s literally a wrapper around WiFiClient and ArduinoWiFiServer which is based on the WiFiServer class of the ESP8266 Arduino core and has some code for handling multiple clients. But there’s no handling of any of those special RFC2217 formatted packets in there as I see. (source: see here and related source files).

So just tell to connect to a pure TCP socket.

monitor_port = socket://IP-adr.local:23

Works! Thanks for the help!