Hi rus4u, I understand that sync stopped working a few days ago on two devices. *Were there any error messages that you received? *And if you click or tap "Sync now" on either device, do you see any changes in the data that is synced? *If you unlink the account from one of the devices(make a backup [[Back up and restore information in Firefox profiles]] ) and reattach the account does the syncing continue? If you need to troubleshoot further: * How do I turn on sync logs: # Open about:config and turn on: services.sync.log.appender.file.logOnSuccess and services.sync.log.logger.engine.bookmarks # Restart Firefox and look at: about:sync-log # Logs and error messages will be located here