I too just returned from this Norway northern lights cruise, and it was my first experience of the new internet charging policy. Our diamond credit was only equivalent for six days use each so I had the first six days, and my wife the second six days. Once purchased the daily 20 dollar access can be used on any number of devices, but only one at a time, so as long as I logged out on my phone, my wife was able to use the same account on her phone. You only need to purchase a ‘second device’ access if the devices are used concurrently.
We too thought that the daily charge was a bit much, in that we only sent the odd email message etc so could easily have got by with an hour a day, as we are not of the younger generation that seem to need 24/7 access.
incidentally, re the IT issues. We were on deck six with identical phones, my wife’s phone worked in the room but mine didn’t! No problems in public areas such as deck 7, commodore club, theatre, illuminations though.