Hi, Shramik. Thanks for the directions. I’ll try to get one f the supported Ethernet shields, although in this topic it is mentioned that mine should work as well :
Does it support ENC28J60 module?
I’ve read your project a few times already, but I have no idea how to replace the pass code for opening via Cayenne. I imagine it should be a kind of field in the Cayenne window. And when I type the numbers in that field, they are “magically” sent to Arduino and stored in the EEPROM, replacing the existing pass code… 
Any advice?