Hello!
ok, it's quite simple to resolve
Jan 28 19:40:34 efw mm-helper[uplink1]: Failed to connect: org.freedesktop.ModemManager1.Error.Core.InvalidArgs: Invalid properties dictionary, unexpected key 'username'
From the Mobile Broadband uplink configuration, remove the username and password that automatically fill the system and then save. Then the connection should work properly
Which provider are you using?
Daniele