Thanks @phileep
So now it seems to work, I’ve loaded ESPEasy Build 20100 - Mega (core 2_3_0) on the ESP8266 side and latest version of RFLink firmware in the ATMega side of the board.
After initial configuration of ESPEasy (Wifi and other stuff), I’ve added into the Devices tab a “Communication - Serial Server” setting a TCP port and choosing RFLink as Event Processing".
Then in the configuration.yaml I just added:
rflink:
host: 192.168.1.167
port: xxxx
and all is working.