Sorry for that long time, I didn’t have Internet access. I’m not quite sure of where did I find the EUI, I’m going to take a look to see if I find it so I can help you, that shouldn’t be a problem I hope…
Yes, I think there’s a way to do that, but it may not be recommendable to send many downlink messages from your server (using TTN) to your nodes.
Downlink messages should be avoided if possible, and if you send downlink, keep the payload small
However, what client are you using in your server?