We currently have Vodafone 100/20 Fibre in Lower Hutt region which when working we are getting consistient data throughput, however we are continually having the connection drop for around a minute throughout the day. When the connection drops I can see the 'Optical' LED on the ONT flash orange as it re-acquires a connection. This is really frustrating when we aree watching Netflix, on a Skype call, etc.
I create a script that monitors the dropouts and it seems to be about 12 times a day with no specific pattern. There was one period where we had 11 drops in a half an hour period, but otherwise they have been spaced out. Below are the times for a 4 day period recently...
If it is an optical fault (physical fibre link itself is dropping), as it sounds by your description, you will need to call Vodafone and get a fault logged for the LFC (probably Chorus, depending on your area) to investigate. Could be dirty fibre or failing connector or failing ONT or something else.
We are in Central Hutt, and have had this problem on and off at my office over the last year, but also at my home 1 km away. We are on fibre at home and cable at home. The vodfone people were very unhelpful, and insisted that I install a new modem. The problem has returned over the last month.