Without watching the video, but having set up ZeroTier on a couple of OpenWrt routers, I’m assuming that this is a similar situation and he is bridging or routing his LAN into a ZeroTier network.
I might be able to help if you provide some more information about how it’s not working for you (i.e. what seems to be going wrong).
EDIT: Looked at the Teltoniks documentation and it’s even more straightforward to set up ZeroTier than it is in OpenWrt (Teltoniks has a nice GUI for it). So I’m guessing your problem is either with establishing a connection at all, or bridging/routing the Teltoniks LAN into your ZeroTier network so you can access the radio. The first might be hard, the second is probably easier.
As per the video Teltonika know how to set things up but when I approached them they said that they were not interested in helping me with any further information and suggested I went back to the original supplier for help. To be honest they had no idea ! - I have ditched everything Teltonika now and looking at other router that may have a better following to offer assistance.
In terms of getting assistance with the router configuration, I’d strongly suggest something that can run OpenWrt. Their community is usually pretty active and helpful, and OpenWrt gives you a lot of flexibility. It’s supported on a huge range of devices.
Mikrotik natively supports ZeroTier now too, I think, but I’ve been warned that their RouterOS is less user-friendly for non-sysadmin types (which is definitely where I land).
