serial.write to esp8266-01 esp easy

[Robert]

Hello forum, as this is my first post it may be wrong named and/or wrong addressed. Please advise how to improve

The question/problem: I cannot get esp easy /esp8266-01 get to read the serial output of my arduino pro mine (deek-robot).
Environment: Domoticz, MQTT, Esp easy on esp8266-01 (several), arduino uno, deek-robot (several, sensors (several). P1 OK, though values are way off, weather is working, MQTT OK.
The app: " kind of greenhouse" : when the soil is dry==> relay for water, when too cold (by wet-bulb temp!) ==> relay for heating.
The wet-bulb temp is calculated based on temp, hum and press (2 sensors, no bme280 available right now).

The calculation and relay steering I left to the deek-robot. I want to use that board also to put the esp on/off saving battery power, (function is crucial when it's cold)

I've been searching now for weeks but cannot find the solution and I want/like to stick to ESP Easy as I see the benefits and want to embrace the work done.
The solution should be quite easy and I feel quite stupid I cannot solve it.

kind regards, Rob