Update firmware SC to V01.00.0820 over Wifi

I fly a M2P with the SC. For some ore other reason my SC won’t connect to my PC (W10 Proff). So I try to update the FW of the SC (to version V01.00.0820) via Wifi (at my home). But I got infinitive messages “Note Network Error - Download Stopped”. After that you can touch the buttons “OK” and “Continue Download”, but the process went so slowly and there were so many interruptions with this message that it became an impossible job. With my iPhone and iPad the Wifi is working without problems. Any remarks/advice?