CEO of Ultrafast Fibre John Hanna said Whanganui's usage matched other major towns.
"It's performing as everyone else is at this time."
Whanganui was one of the first centres to have fibre installed in 2014. 21,000 homes in the area are able to connect to fibre services, but not many households are making use of the service.
"At this time only 10,200 are active on our network, around 48 per cent."
For comparison, Hamilton and Tauranga were both over 65 per cent.
Getting people on to fibre had always been a challenge in the area, Hanna said.
"Whanganui has historically been a highly digitally engaged community. There has been a huge emphasis on innovative business with the local council very keen to support innovation and business growth.
"So it is somewhat puzzling to us that we don't have a higher uptake of fibre across the community, particularly at this time."
A "fairly significant investment" was made before the Rugby World Cup as Government and shareholders were nervous with how the network would perform.
That upgrade has Hanna very confident in the network and system for the weeks ahead.
"Currently under 35 per cent of our network is being utilised. Not worried at all," he said.
Hanna said since Friday the traffic had dropped off, but he could see that picking up depending on the weather.
"It's dropped to the 'new norm', and is sitting around the same level as what it was during the Rugby World Cup.
"If we have a cold snap and a really rainy day across New Zealand, I think we will see another spike. It certainly isn't going to stress our network at all."
Hanna said the focus was on ensuring essential services remained online during the lockdown, and they would take priority in service.
"Our connection focus and fault repair focus are on ensuring those services are well-supported and respond quickly and safely."