When ipv6 and v4 are both available, how to use ipv4 but ipv6

Tailscale version 1.30.2

My network is have ipv4 and ipv6, the ipv6 of my device is public and ipv4 is NAT , but the ipv6 is not fast and not stabilize. So I want use ipv4 not ipv6 to connect each other.