I get on the ferry quite early (before anyone else often) at about 6:50am. First thing I do is check emails, then facebook, then I read a book or talk to others.
While there are very few people aboard the ferry (say from 650-700), 4G on my phone works fine (I can watch silly cat videos on Facebook etc). Once the buses get in and the ferry starts filling up (maybe coincidence, but happens after about 10 minutes for me, and others I sit with in the morning), my phone shows full signal (5 dots on an iPhone 6) and the 4G symbol, but I cannot get anything on the internet. Facebook doesn't work, emails won't delete/move folders, NZ Herald app will not load etc. It is not just me, everyone I talk to that is on Vodafone has the issue. This is while the ferry is still docked (so has not moved out of range - pretty certain there is a Vodafone cell tower in the bay). Once we start moving (at 715) signal drops down as we leave the bay (understandable) and then picks up as we get closer to Auckland (obviously then coming off a city cell tower as it can only be 1 or two bars until we get past Rangitoto), but the whole time it is on those one or two bars, the internet works fine.
This happens every day, and the same behavior is seen when I return in the evening - full bars within the bay, but no internet (haven't tried a call actually, but iMessage certainly doesn't work).
I think someone at Vodafone needs to know that there is an issue with their cell tower at Matiatia (or they need to tell us that it cannot cope with 200-400 people checking facebook at once :p)
AFAIK no one on Spark has any issues. 2D do, but I think on Waiheke they roam to Vodafone.
What would be the best way to make someone high enough up at Vodafone take note? I did try their helpdesk once, but gave up when they did not understand me. I think the above is pretty clear.
Maybe one of the great Vodafone tech people here should organize a trip to Cable Bay for dinner one night and see what I'm talking about when the ferry docks and they can't update their statuses :)