As a small but noticeable extra kink, SMS messages are showing error, unsent locally on our phones although it seems they are receiving them and the error message is itself, erroneous aha. I have checked this with multiple networks. Just thought i'd throw that in there too. Begun at the same time as the other issues
Yep, that's about the size of it. No 4G whatsoever for last couple of days, and no 3G either. Have to use wifi if data is needed, impossible in shops most of the time, and you cannot use Android Pay either for time being. It might also explain why texts are sometimes delayed for up to a day, e.g. sms to wife in the afternoon/evening saying I'm delayed is not received until next morning!