UMTS/LTE in Leap 42.1

Hi,

I have a Fujitsu E744 notebook (certified for SLED according to datasheet) with a Sierra Wireless E7305 3G/4G modem. lsusb says:

Bus 002 Device 003: ID 1199:9041 Sierra Wireless, Inc.

In Leap 42.1 I can choose my provider from the list in plasma-nm/editor to configure the WWAN connection, but the Connect button at the top stays greyed out.
I don’t get how to enable the connection actually.

Can you give me a hint?

Thanks.

Best,
lem64