Not sure if I'm missing something obvious here, but I see an industry listing a connected stop (freight) more tiles away than the settings in station_coverage_factories.
Screenshot is here: http://files.simutrans.com/index.php/s/PLEmFRyg1wibazg
The furniture factory is 5 tiles away from the nearest freight stop but is connected, the furniture shop is 4 tiles away but not connected.
I think that the coverage is not square, but a diamond shaped. The furniture shop is 4 tiles south + 2 tiles east of the station, i. E. 6 tiles away.
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