You have a network printer that does not support Airprint. You want to print to it from your phone.
A linux box. This page shows you how to do it on Debian.
Install a print server on your linix box:
sudo apt install cups
Note that CUPS requires Apache to run the web based UI. If you don’t already have it installed:
sudo apt install apache2
If you’re running headless, you will need to allow remote administration:
sudo cupsctl --remote-admin --remote-any --share-printers
Add yourself to the lpadmin group:
sudo usermod -aG lpadmin username
Restart CUPS:
sudo /etc/init.d/cups restart
This should allow you to log into the web UI on port 631.
Access the web UI and use the Administration menu to add a printer and then share it. Give it a unique name.
Airprint should work out of the box.