Crossplay on a Valheim Server: One Flag, Three Identity Systems

 

    Valheim crossplay is switched on by a single launch argument, -crossplay, and there is a widely repeated claim that it is "opt-in, not the default." That is half right in a way worth correcting: the argument is required, but it is already present in the example launch scripts that ship with the dedicated server. So on most setups it is on unless somebody removed it.

 

    On sourcing. Iron Gate do not publish system documentation. The figures below come from the community wikis and can change with any patch.

 

The Flag

 

 

    The wiki states it directly:

 

Crossplay is engaged by adding the -crossplay argument to the server command line. This is the default in the example launch scripts that ship with the dedicated server.

 

    Two things follow, and they are easy to conflate:

 

• The argument is genuinely required. Without it, the server is Steam-only.
• It is already there by default. The shipped example scripts include it, so a stock configuration has crossplay on.

 

    For the panel-side steps, see How to enable crossplay on a Valheim server; for what 1.0 changed about who can join, see Valheim 1.0 Crossplay: PlayStation 5 and Switch 2 Join the Party.

 

    The practical question is therefore not "how do I enable crossplay" but "has anything removed the flag." A hand-written launch line, a migrated configuration, or a panel that builds its own command line are the three places it goes missing.

 

Three Identity Systems

 

    Crossplay changes more than who can connect. It changes how the server identifies people, which has direct consequences for your list files.

 

The server can connect, identify, elevate or ban players using their Apple Game Center, Steam or Xbox Live identities.

 

Platform family	Identity
Steam	steamID64
Xbox and Game Pass	Xbox Live identity
Apple platforms	Apple Game Center identity

 

    That is why a crossplay server's adminlist.txt may contain entries that are not steamID64s. The file's documented format is steamID64, but the identity a player presents depends on where they connect from — so ask each player for the ID matching their own platform rather than assuming Steam.

 

    A player who owns the game on two platforms may need two entries if they switch between them.

 

What 1.0 Added

 

 

    Valheim 1.0 brought PlayStation 5 and Nintendo Switch 2 into the game with full crossplay across every platform. That widens the identity picture again and makes the flag more consequential than it was — a Steam-only server now excludes considerably more people than it used to.

 

    For a mixed group, crossplay is not optional in practice. The flag costs nothing, the shipped scripts already have it, and turning it off only narrows who can join.

 

What Crossplay Does Not Do

 

    Being precise about the limits, because they generate support questions:

 

• It does not change the password. Crossplay servers still take a server password like any other.
• It does not change the list files' location or format. They stay in the same folder, one identifier per line.
• It does not change save files. The .db and .fwl pair is platform-agnostic.
• It does not affect mods. If BepInEx mods are installed server-side, every connecting player generally needs matching mod versions client-side — and console players cannot install them at all, which makes a modded server effectively PC-only regardless of the crossplay flag.

 

    That last point is the one worth planning around. A modded crossplay server is a contradiction in practice: the flag lets console players connect, and the mods stop them.

 

Deciding for Your Group

 

 

• Leave -crossplay in place. It is the shipped default and removing it only excludes people.
• Check the flag if console players cannot connect. That is the first thing to look at, not the password or the port.
• Collect the right IDs for your list files — Steam, Xbox Live or Apple Game Center depending on the player.
• Choose between mods and console players. You can have BepInEx or a genuinely cross-platform group; not comfortably both.
• Remember PS5 and Switch 2 arrived with 1.0, so the audience a Steam-only server excludes is larger than it was.

 

Running your own Valheim server

 

    Crossplay is one line in a launch configuration, which is exactly the kind of thing that should be a toggle rather than a text field. A gamever Valheim server keeps it that way, for up to 10 players, with one-click backups and automatic updates.

 

Conclusion

 

    Valheim crossplay is engaged with the -crossplay launch argument, and the common framing that it is "opt-in, not default" is misleading: the argument is required, but it already appears in the example launch scripts that ship with the dedicated server, so a stock setup has it on. The real question is whether a hand-written launch line, a migration or a panel-generated command has dropped it. Crossplay also changes identity, since the server can connect, identify, elevate and ban players using Apple Game Center, Steam or Xbox Live credentials — which means a crossplay server's adminlist.txt may hold entries that are not steamID64s, and a player on two platforms may need two. Valheim 1.0 added PlayStation 5 and Nintendo Switch 2 with full crossplay, so a Steam-only server now excludes more people than before. The one real incompatibility is mods: server-side BepInEx generally requires matching client versions, which console players cannot install — so a modded server is PC-only whatever the flag says.

 

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