I am having the same issue as the OP, ledoktre. I disabled the relay, tracker, and DHT settings for a folder on the only two nodes (iMac & MacBook), and my iPhone was still able to sync the folder while not on the LAN (only on LTE). Also , the iPhone does show in the devices tab on the desktop software. This is problematic since the mantra on these forums has been that disabling these 3 settings will limit sync to LAN only. This appears to not be the case. I then followed ledoktre's more stringent setup instructions in the previous post. Once, my computers were re-connected to the internet, they were not able to sync at all. So, at this point, I am not sure how to actually sync only on LAN. I hope someone from BT Sync will chime in to provide more clarity about what is going on here and how to actually achieve LAN only sync, if possible.