Cool! To get the best performance out of zerotier I used the same cellular network for the ground station and the plane ie. Two sim cards from the same network, one for the planes modem and one for my laptops modem. Remember that ZeroTier doesn’t work with Symmetric NATs. So you just hope that the cellular network you choose doesn’t use symmetric NAT (90 percent of NAT is not symmetric). Ideally if both plane and ground station are on the same cell network, then ZeroTier is able to work within the “LAN” of the cell network (doesn’t have to go through multiple NAT services) and latency is decreased. (My latency was about 300ms – 450ms for video over 4g (and around 150-200ms for a direct wifi connection just because the pi 3+ takes a moment to manage the video), but I had a constant steady connection and that is plenty fast to enjoy flying a plane with autopilot). Check out this article: https://www.zerotier.com/2014/08/25/the-state-of-nat-traversal/ and specifically the section titled: “The Same Network Problem”. My explanations about NAT and ZeroTier may be off, but this is how I currently understand it.