How to install ZeroTier on Teltonika RUTX.../TRB... routers

You can install the ZeroTier using the LuCI webinterface and opening Services->Package Manager. On that page, install the ZeroTier package.

Then configure ZeroTier using Services -> VPN -> ZeroTier. First, add a new zerotier interface and then add one or more networks. Typically you can leave other settings as default.