Question: I have downloaded this file : ubuntu-18.04.3-desktop-amd64.iso to install Unbuntu on an old computer. After startup, I have had this message : This kernel requires an x86-64 CPU, but only detected an i686 CPU.
Unable to boot - please use a kernel appropriate for your CPU.

Is it related to my CPU capabilities ? May I install an 32 bits version ?
If yes, is it possible to have Unity as 32 bits version ?

Answer: 
The usual way is to sign up for a [DDNS service](https://en.wikipedia.org/wiki/Dynamic_DNS), with that service's application running on your home server.

The DDNS service and application work together to update your public IP address (which means your *router's* IP address) to internet nameservers.

So you use `ssh me@myserver.myDDNSprovider.com`, and the nameserver provides the correct IP address for your router and LAN.

* Several free DDNS services are available. Your favorite search engine will happily point you to several.
* Many consumer routers have DDNS clients built-in, so you needn't install anything on your server. Check your router settings.
* You must still set up *port forwarding* on your router to connect to the server on your LAN.
There is a service called <https://ngrok.com/> which allows you to set up temporary tunnels for various protocols. Basically, you'd open an SSH tunnel to the local SSH server on the host you want to connect into; this then exposes the tunnel to the public network. You obviously have to do this when you are connected locally, but after that, remote access should be possible.

Their (brief) instructions for this are at <https://ngrok.com/docs/using-ngrok-with#ssh>

Obviously, you have to be careful not to expose services which are not properly secured, or you will be having visitors.