web development – lost Ethernet connection then work on localhost

It is therefore possible to insert data or create files in case of loss of connection .. (Web Application (PHP)).

Example of domain name test.example.com / IP

So, if the Ethernet connection is lost, I can still use a web application like inserting data into files (PHP form data in a file).

Ethernet disappears after 2 hours and workers can still insert data from the website (for example, it works offline localhost and if the Ethernet connection is reestablished, it is online and visible from the domain name or the IP address; it's offline, localhost IP or just "localhost").

This is possible?