Please help us help you and fill where relevant:
Your LimeSurvey version: LimeSurvey Community Edition Version 6.4.6+240212
Own server or LimeSurvey hosting: Own Server
Survey theme/template: Custom
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Hi, my team is working on a solution that involves needing limesurvey in only closed access mode for all surveys, as they all need a participants table with a token. Is there any suggestions on ways to only have closed access mode for all surveys or will we have to find a custom solution?

Thanks

There is currently no way to enforce closed access mode, so I think you will need to do a custom solution.
Is is security sensitive?

If not, maybe place some JS that will close the survey by doing the necessary clicks after activation? You would also need to hide the button to delete the participant table.

If you want to enforce it server side, then you will most likely need to code a proper plugin.

Disable all access to survey without token table in www.limesurvey.org/manual/BeforeSurveyPage via a plugin seems very easy.