Just thought I post this, in case anyone else has similar problems in the future.
A while ago I had enormous difficulties getting my emonTX / ESP8266’s to connect to my Apple based wifi network. So much so that I had to invest in several Airport Express APs & locate them merely a couple of centimetres from the emonTXs. All a bit of a palaver but at least it worked. IIRC at the time, someone mentioned something about possible issues with Airports not playing well with emonTX/ESP8266’s, but I chose to ignore that advice
I have recently moved my network from Apple to Unifi hardware, and I have been able to remove the co-located Airport Expresses. The emonTX/ESP8266’s seem to be able to work with higher -Db (ie lower signal strengths?) than they did within the Apple ecosystem, which is great news.
So, if anyone else has similar issues, do consider not using Airport APs …