Before buying a copy for a specific platform, it is worth separating crossplay from cross-progression and cross-buy. All three are different.
Regional differences occasionally split matchmaking in ways that look like a platform issue. Purchased content is tied to the store it came from even when the save is shared.
Short version
Matchmaking generally crosses platforms; invites, voice chat and purchases generally do not.
How to set it up
With opt-in crossplay, one account that has it disabled breaks the whole group silently. There are two questions inside is sea of thieves cross play: playing together, and carrying progress. They have different answers. If you are following this with someone else, agree on the plan before starting rather than mid-run. Where a game has a mobile version, it is usually the one that lags behind on updates.
Where it breaks
A publisher account is free, and setting it up before a session avoids the usual ten-minute delay. Where opinions differ, the disagreement is normally about priorities rather than facts. The support page for is sea of thieves cross play is the most reliable source and the least readable one.
Buying on one platform rarely entitles you to the game on another. Most confusion about is sea of thieves cross play comes down to one person in the group never linking an account.
- Check console parental or privacy settings if one person cannot connect.
- Create and link a publisher account on every platform involved.
- Have a fallback plan for the step most likely to fail.
- Link accounts before the session rather than during it.
- Check the version you are running before following any step-by-step advice.
If someone cannot join the group
Where crossplay is opt-in, it usually needs enabling on every account rather than just the host's. Subscription requirements for online play differ by platform and catch out mixed groups. The version you are running matters more than the platform you are running it on. Console family restrictions sometimes allow one generation and not the other.
A shared account is usually the requirement, and creating it later than your friends is a common source of confusion. Handheld or mobile versions often lag a version behind, which breaks parity temporarily.
Which platform to buy on
Where crossplay is optional, one person leaving it off breaks the group silently. Some modes support crossplay while others in the same game do not. Give the first attempt an honest try before deciding the method does not work. Friend codes work more reliably than platform friend lists for exactly this reason.
Progress carried across platforms usually excludes purchased currency, which surprises people. Publishers announce crossplay loudly and remove it quietly, so recent information matters.
- Note the exact point where things stop matching the guide.
- Write down what you changed, so you can undo it if the result gets worse.
- Check whether the mobile or handheld version is a build behind.
- Check the region setting if matchmaking never finds the group.
- Agree on a server region if the group spans countries.
Avoid these
- Troubleshooting for an hour when one account was never linked.
- Using platform friend lists when the game provides friend codes for this exact reason.
- Making a permanent change when a reversible one would have answered the question.
Other things people ask
Does progress carry over between platforms?
Only where the game offers cross-progression, which is a separate feature from crossplay and less common.
How long should this take?
Most people get through it in one sitting. The first attempt runs long because of reading; the second is much quicker.
Can I turn crossplay off?
Where it is optional, yes, in settings. It usually changes queue times, sometimes considerably.
Is there any risk to my save?
Not from the steps above. Backing up first is still sensible if the game makes it easy, purely because it costs nothing.
If a future patch changes something here, the reasoning should still point you at the fix.