Not appearing in the Server Browser and Steam? That’s a know issue, it will be fixed for the next games, but for Exiles there would be way too many things to change for this to be safe.
What I recommend is to setup a Discord webhook, with a “Ready” message set to something like “The gates to {servername} are now open, please join us on {steamconnect}”, as soon as your server is ready, Discord will receive a message with a clickable link, people just need to click on it to direct connect to your server with the correct password.
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