@R1D2 Thanks for this, makes sense. I need to look around for some different kit suitable for an outdoor relay - just a question of finding a solution which does the job without costing too much....

I have already a CPE210, installed, working OK. But there is a thick stone wall which blocks the signal at a distance of 50m. I am researching the use of a 2nd CPE210 to overcome this problem and...