I think the host of many of the posts here is that the network is the issue and the other things are just symptoms.
Your can threat the symptoms, but without removing the root cause you will just get issues again.
you are absolutely right.
fortunately it is pretty easy to place a wifi access point near the device just to find out if the network is really the issue 
can you explain your setup? What esp model and antenna that worked for you?
https://products.espressif.com/#/product-selector?names=&filter={"Antenna":["IPEX"]}
And choose development boards in the button above the product list.