Hello everyone. Many thanks for your feedback. It could really be the mobile phone. Your answers have helped me a lot, so I won't try anything else and will look for another solution instead. Have a nice day

I tried for days and also without getting it successfully working. I think the problem is that it won't work on 4G/LTE (that's how I use the router exclusively), only via cable connection, because of how mobile network infrastructure is set up in Switzerland. But I cannot say for sure, it is just my hypothesis. I wonder if anyone tried it with the cable internet connection.

Good day Michael, no I was installing it for days! I was also with Netgear support (with expenses involved), but they hadn't managed it either! I was able to return the device and was refunded. https://www.netgear.com/support
Sorry I couldn't give you a better response.

Best regards
Anita