Having just quoted the Act in reference to another question, I am happy to do so again:
108 Changes to common property
(1) Procedure for authorising changes to common property An owners corporation or an owner of a lot in a strata scheme may add to the common property, alter the common property or erect a new structure on common property for the purpose of improving or enhancing the common property.
(2) Any such action may be taken by the owners corporation or owner only if a special resolution has first been passed by the owners corporation that specifically authorises the taking of the particular action proposed.
Note.If the special resolution is a sustainability infrastructure or accessibility infrastructure resolution fewer votes may be needed to pass it. See section 5(1)(b).
Installing fibre to the building must be a change to common property, so a special resolution would be required before work commences.