Start with the device role and session state you can see.

Email support with your browser version, the desktop app version if you installed it, the device names involved, and the error code you can see. support@reallexi.io

Send suspected vulnerabilities to the security address. Do not include customer session content. security@reallexi.io

Report device roles, connection-state label, direct or TURN path, and timestamp. Redact tokens and personal data.