No official retrofit option: Volkswagen does not offer an official retrofit or conversion from the 3G OCU to 4G for older Golf 7 models.
Issue: The OCU is permanently linked to the vehicle identification number (VIN) and the infotainment system. A simple hardware swap will not work, as the component must be programmed and activated on VW servers.
Consequences of the 3G shutdown: Following the discontinuation of 3G (and soon 2G), the affected Golf 7 models will lose their connection to We Connect / Car-Net, rendering features such as vehicle status, app-based auxiliary heating control, and online traffic data unusable.
Alternative solutions: There are no official VW updates to upgrade the OCU module to 4G. Affected users are mostly reliant on alternatives such as App-Connect (CarPlay/Android Auto) to access online services via their smartphone instead of through the internal OCU.
Legal situation: VW notes that services will be discontinued starting in 2025 due to the 3G sunset for many older E-models and the Golf 7.
In summary, physically replacing the 3G OCU module with a 4G module—whether done independently or by a third party—is technically extremely complex and, due to the necessary online coding at VW, generally cannot be successfully carried out.
In other Words...forget your idea before it starts too complicated and you loose Time/Money and Nerves...