Zerotier behaviour is different in LAN and WAN

Hi there
I am setting up two satellite receiver boxes with zerotier.
In principle it works, but:
I did the setup inside the same LAN, and used diverse traffic between the boxes through the zerotier addresses, like https, ssh, samba-mount.
When separating the two boxes into two different LANs, it still works somehow, but extremely slow, and this has nothing to do with the different speed of the LAN connections to the Internet.
It looks like, that zerotier uses still some LAN traffic, when the boxes are in the same LAN, although this would not make sense at all. Any idea?
Thanks for any hint.

ZeroTier uses peer to peer connections and aggressively searches for the fastest/lowest latency connections between peers to use. So if two machines running ZeroTier are on the same LAN, the local LAN address would be preferred. When devices move, other nodes will still try to contact them at previously known addresses for a while in case they reappear there.

As for slowness when moving them to separate LANs, you could be running into some Peer to Peer connectivity issues. Since the machines are no longer attached to the same LAN, they have to be able to contact each other directly over the public internet. If you have a router or firewall in the way, that could hinder those efforts. You’ll need to ensure your router/firewall either has uPnP or NAT-PMP enabled, or add direct port forwards in the router for ZeroTier. You’ll be able to tell if nodes can or cannot make direct connections between each other by examining the output of zerotier-cli peers on the command line. If the ‘Link’ column says “DIRECT”, a direct connection is being made and used. If it says “RELAY”, it’s forwarding its encrypted packets via root servers and this will slow things down a bit. For some tips on configuring your router, see the following article in our knowledge base