I am having the same issue using a NANO and Mini 5100. If anybody has some working code, would you please share. I can get everything working if I use a UNO instead of NANO. The NANO and 5100 shows up on my network but is not talking to MySensors. I am trying to integrate into VERA.
Thank you.

Thank you for your reply. If I am looking at this code right, you have 4 inputs and 4 outputs, is this correct?

Use a latching relay. Here is one I found on Amazon. https://www.amazon.com/dp/B015MRQNXS/?coliid=I3LXTGKX4GEPUR&colid=31WWM91JAUE22&psc=1&ref_=lv_ov_lig_dp_it

If you are trying to use with existing 3 ways use https://www.amazon.com/dp/B015MSYQ8Q/?coliid=I3RP8X9OMYWU97&colid=31WWM91JAUE22&psc=1&ref_=lv_ov_lig_dp_it

Use an optocoupler to indicate lamp status...see the last diagram in this post. https://forum.arduino.cc/index.php?topic=435506.0

Hello,
I am new to this site. I was directed to this site from the VERA forums. I am trying to integrate an Arduino with VERA. I am reading about the different Gateways and such. The Ethernet Gateway looks good but I do not need the wireless / radio devices. The project I am trying to accomplish....I have 2 out buildings out of range of ZWave and WIFI but I have Ethernet cable run to each of the buildings. I would like to put an Arduino in each of the buildings. I need about 6 digital inputs and a few digital outputs on each board. Door switches, etc. Nothing fancy here. The buildings are pole buildings so running wire is very easy. I saw the examples relay control and door/window button. I would like to combine the 2 without the radio units. Basically, use the I/O on the Gateway Arduino. Is this possible? Also, is it possible to use 2 Ethernet Gateways on a VERA? BTW I have the MySensors Plugin running / installed and running on Vera. I have a basic understanding of Arduino. Any suggestions / comments / directions would be greatly appreciated.
Thank you.