This is a way to have it, but this is often a data written in the VPS provider doc.
For instance for ionos it’s always in ipv4 :
netmask 255.255.255.255
gateway 10.255.255.1
in ipv6:
netmask 64
gateway fe80::1
Note that I also wanted to make a guide that does not depend on the provider. That’s why I didn’t specify the specific actions for Ionos.