Strange with ipv6

[Comandante1977]

Hi!
I know that my my question more relative to server config, but maybe smb will help me.
Installed xray (via 3x-ui) on one testing server. Everything works as expected.
Installed on other (manually with same config) and it not working. After some research
I found that server is not mapping ipv6 address to ipv4. If I have no option "listen" or
have "listen":"0.0.0.0", then client (havent ipv6) dont want to connect. If I have "listen":"ipv4 address"
then everything is ok. Bindv6only is set to 0 in server's config. IPv4 priority is set to high than ipv6.

After testing I want dual stack functionality. So, I missing smth in configs.

Any suggestions.