How to make ipv6 default?

Question

Network administration

Good day!
Configured zyxel router to use ipv6
disable ipv4 everything works fine
But the trouble is that all services use ipv4 as preferred.
How to do it so that at first the request would be on ipv6, but only in case of failure on ipv4
firefox win10
neither on the router, nor in win10 nor in firefox, no matter how much I dug, it was not possible to find
and Google is treacherously silent

Answer 1

The priority is determined by the OS. Windows prioritizes using IPv6. Those. IPv6 will always take precedence if available.
How do you make sure that you have priority over IPv4?
ipv6-test.com