How can I link users across multiple subdomains?

The fact that you haven’t mentioned MultiSite in your post makes me think that doing some research there would be a good next step for you:

https://codex.wordpress.org/Create_A_Network

User Accounts are shared across sites in the network, and sites can be different subdomains.

Related Posts:

  1. Multiple Single Installs of WordPress with a central user base
  2. Editor can create any new user except administrator
  3. Confirmation required on email change
  4. get_current_user_id() returns 0?
  5. List users by last name in WP_User_Query
  6. Email user when password is reset by admin
  7. How to use alias domain for multisite installation?
  8. How to work around “that email address has already been used” error?
  9. How can I run a WP-CLI command as authenticated user?
  10. LEFT JOIN, INNER OUTER JOIN, LEFT OUTER JOIN is driving me crazy. Please help?
  11. Upload gravatar in WP profile?
  12. How to stop a user from updating the post date
  13. Recover the user that have been deleted
  14. determining if the user is logged in
  15. Check if user is online?
  16. How to check that if current user (ID) has posts or not
  17. How to get the Role Name of the current user? (WordPress)
  18. how to get recent registered author id?
  19. set_role has no effect
  20. Is it possible to duplicate users on a new WordPress install?
  21. Why don’t first_name and last_name appear when you print_r the WP_User object?
  22. Changing default Buddypress avatar affects all site avatars (because gravatar)
  23. Custom style on profile options page
  24. Best way to have an per-user customized private section
  25. How to query users who have empty first_name?
  26. Post as someone else
  27. How to make user accept license agreement before download
  28. Does wp_delete_user() remove all user content?
  29. 14,000 WordPress Users. How did they get there?
  30. Adding second Email address for WP user notifications
  31. wp_login_form() passing user ID into URL on redirect?
  32. how to make a profile entry read only except for site managers [closed]
  33. Managing Users and Creating Groups [closed]
  34. Users: List A to Z, for Users
  35. Upgrade Nightmare – No Posts, Permissions Issues and Can’t Create a new post
  36. Max no of simultaneous active sessions for a single user
  37. WPML Default Language User Meta [closed]
  38. Search Users base on meta_value & meta_key
  39. Favorite taxonomy archive page?
  40. Fix permissions for users role
  41. Redirect subscribers to last viewed page after log-in
  42. User Meta Data in a Sortable Table
  43. Are there mutiple ways to get usernames (as a hacker)
  44. Rest api return all users (even without content) to all users
  45. Column Sorting Code on users.php
  46. How to stop redirect if user is already on correct page (Using Case Switch)
  47. search users using user name and user meta in wordpress
  48. Where are $current_user->allcaps set?
  49. How to activate the user search
  50. How change user type from contributor to author
  51. WordPress Login Customization for External Authentication
  52. How to allow registered users to submit the form only 5 times per day?
  53. Is there any action /filter hook I can use to disable login for some user role?
  54. Preventing user enumeration: which logic is better?
  55. Create a “user log”
  56. How can I do a url redirect to include a wordpress username?
  57. WP_User_Query combining role and ids
  58. Allow Users to Modify Some Values of Assigned WordPress Pods [closed]
  59. Can I Create a Second Admin Level User Role?
  60. Custom registration and pending approval
  61. Let logged-in users use radio buttons (yes and no) to exclude their author profile from the user listing
  62. Adding fields to the “Add New User” but the form data not saved into DB
  63. Admin approval for editing user profile
  64. Using a custom field value as current users name [closed]
  65. How would I restrict certain user levels from editing categories
  66. How can I set wp_dropdown_users so that it shows only authors?
  67. WP Create User – Preventing repeated information
  68. Editor role can only create/edit/delete users who have one of two roles
  69. Can’t add user- wrong message “this user name is invalid because it uses illegal characters”
  70. WordPress 5.8 – Hide or Remove personal fields from admin Profile page
  71. hide user is currently editing warning in admin post page
  72. Restricting wordpress login sessions for a web app
  73. change user password REST API
  74. Use WP cookie to authentificate user on an external app
  75. Find count of WordPress users by role and search string for user name
  76. Append USER ID to an outbound link?
  77. Users activity history
  78. How to destroy all user sessions via WP-CLI
  79. Is a list of user names or IDs in a custom profile field the best way to create a followers list?
  80. Custom User Role: Can Edit Own Page, Cannot Create New
  81. Get meta key with value for user
  82. Redirect current user
  83. Display Users and user url’s
  84. custom login form, guide me
  85. Edit dashboard based on user ID
  86. Get the author registration date in the header.php file
  87. Front end login and page restriction
  88. How i will get the images of highest scored users?
  89. Designing a member area on my site
  90. Link to Authors blog posts
  91. view and update form only for registered users
  92. Redirect based on log-in status per JavaScript
  93. i need to let a user to add a role from a frontend form
  94. Integrating Facebook Registration (and Login) on a WordPress page
  95. WordPress C# User Login
  96. Create users from frontend without password
  97. How to get user contact info
  98. Why does a super admin on multi site get a rest_user_invalid_id error code when requesting user details through REST?
  99. How to allow users to make quizzes or tests in WordPress?
  100. Can we get user profile page using user_id in the URL?
techhipbettruvabetnorabahisbahis forumutaraftarium24edusedusedueduseduedueduedusedusedus