Using com2tcp-rfc2217.bat on Windows and uploading to COM5 via WSL2 (ESP8266) and platform.io not working - wsl-2

Question

Setup on Windows
ESP8266 connected to COM5 port
.\com2tcp-rfc2217.bat COM5 4444
D:\Downloads\hub4com-2.1.0.0-386>"hub4com" --create-filter=escparse,com,parse --create-filter=purge,com,purge --create-filter=pinmap,com,pinmap:"--rts=cts --dtr=dsr --break=break" --create-filter=linectl,com,lc:"--br=remote --lc=remote" --add-filters=0:com --create-filter=telnet,tcp,telnet:" --comport=server --suppress-echo=yes" --create-filter=lsrmap,tcp,lsrmap --create-filter=pinmap,tcp,pinmap:"--cts=cts --dsr=dsr --dcd=dcd --ring=ring" --create-filter=linectl,tcp,lc:"--br=local --lc=local" --add-filters=1:tcp --baud=115200 --octs=off "COM5" --use-driver=tcp "*4444"
COM5 Open("COM5", baud=115200, data=8, parity=no, stop=1, octs=off, odsr=off, ox=off, ix=off, idsr=off, ito=0) - OK
Route data TCP(1) --> COM5(0)
Route data COM5(0) --> TCP(1)
Route flow control TCP(1) --> COM5(0)
Route flow control COM5(0) --> TCP(1)
Filters:
_______
\->{telnet.IN}-------------------------------------------->
TCP(1) | /
_______/<-----{telnet.OUT}<-{lsrmap.OUT}<-{pinmap.OUT}<-{lc.OUT}<-
________
\->{parse.IN}------------------------------>
COM5(0) | /
________/<-----{purge.OUT}<-{pinmap.OUT}<-{lc.OUT}<-
Started COM5(0)
Socket(0.0.0.0:4444) = 204
Listen(204) - OK
Started TCP(1)
Setup on WSL2
VSCode Remote for WSL installed and running fine
platform.io extension in VSCode installed and running
platformio.ini
[env:nodemcuv2]
platform = espressif8266
board = nodemcuv2
framework = arduino
platform_packages =
framework-arduinoespressif8266 # https://github.com/esp8266/Arduino.git
lib_deps = ESP Async WebServer
build_unflags = -std=gnu++17 -std=c17
build_flags = -std=gnu99 -std=c++11
monitor_port=socket://192.168.1.100:4444
monitor_speed=115200
upload_speed=115200
upload_port=socket://192.168.1.100:4444
Problem
I cannot upload anything to the ESP8266
Connecting........_____
When using upload_port=rfc2217://192.168.1.100:4444 the error is:
A fatal error occurred: Failed to connect to ESP8266: Timed out waiting for packet header
When using upload_port=socket://192.168.1.100:4444the error is:
A fatal error occurred: Failed to connect to ESP8266: Invalid head of packet (0x6F)
What works
I can open up the serial monitor and view the serial output of the ESP8266 just fine. So the ports and the baud-rates seem fine to me.
What am I missing here?

Answer 1

I managed to solve it.
For some reason, the ESP8266 is not automatically switching to flash-mode while uploading via rfc2217. I had to put it in flash-mode manually by holding flash-button and pressing reset button while the Connecting...___ shows up.