On my other VPS boxes running Outline, I see the port (say 9999, as in your example) listening on tcp6, but in addition to :::*, it lists 0.0.0.0 on the next row
And they're all running Ubuntu 19.10 ootb at the same VPS provider – which means they should be more-or-less identical
Only difference is this particular box started as 16.04 a couple years ago (and has been through dist upgrades), whereas the others started in the 18.x series (and have been through dist upgrades)
November 10, 2019 at 07:02PM
via reddit https://www.reddit.com/r/outlinevpn/comments/dt0f4c/how_do_i_coconfigure_outline_to_listen_on_ipv4_as/f76mvhv?utm_source=ifttt