Usage slightly dropped on Thursday compared to Wednesday, but was still 10 gigabits more than on Monday or Tuesday.
"We are delighted to see our Whanganui community seamlessly transition to effective work and learn from home," Ultrafast Fibre chief executive John Hanna said.
"This new peak is greater demand than experienced in either the Rugby World Cup or 2020's first national lockdown and shows just how vital reliable online connectivity has become."
Hanna said although there was record overall network peak on Wednesday and Thursday, there was no need to worry as there was about double the capacity if required.
"Naturally we are observing all the Government protocols and putting the health and safety of our people, our partners, customers and the general public first and focusing primarily on protecting the network to ensure everyone can stay online.
"We look forward to being back in the business of connecting new customers as soon as we can, but in the meantime it is a privilege to serve the Whanganui community at this challenging time."