It is difficult to explain this without going technical, because it is.
You’ll need a VPN (Virtual Private Network). There are different solutions, like OpenVPN and WireGuard, and WireGuard is much simpler.
There is a server and a client. The Server needs to be reachable via Internet, all the time. For this Reason, you need two things
- A static IP, or a static Hostname, that is resolving to your IP (called DynDNS, DDNS,…)
- If the Flint is not the Main router, a Portforwarding from The Internet to the Flint.
- Two different Networks
At first you take a look around your network and check if any device is already have had a dynamic hostname. It is mainly used for remote access via App, from NAS devices, security cameras, smart fridge/washing machine/iron and so on. If there is no device, check the GoogdCloud way ([letters and numbers].glddns.com), as mentioned earlier.
Than check if your Flint is the main router, connected to the Internet, or if you need to forward the port. The last one depends on your router.
Now you can start to follow the given manual. First setup the ‘Wireguard Server’ on the Flint, than add a profile for the Beryl.
But before you can go live, you may need to change the IP address of the Beryl. If both ‘local networks’ are 192.168.8.1, the Tunnel (VPN) won’t work. You can change it to everything you want, maybe 192.168.9.1 …
As the server (Flint) will run permanent, and the client (Beryl) will search for the DDNS hostname, the connection will be possible from nearly everywhere, with internet.
For example: It won’t work, if the hotel WLAN only allow web (http) and Email traffic. But such issues are too depending on the specific situation, as it can be discussed here in general.
And I think you should not be able to build the VPN with the Beryl inside your net. If you’d like to test it, either try to tether the internet with your phone (mobile data plan, not WLAN!) or from your neighbors house.