There’s an intrinsic anomaly in all of this which is that an external body (NBN) is dictating strata policy. The law says that common property costs must be charged on the basis of unit entitlements. NBN says the installation must be all or nothing. The OC is responsible (very generally speaking) for infrastructure up to but not into individual units. The OC can’t really issue a compusory charge on any basis other than UEs. And there will be some people who don’t want high-speed internet anyway.
One elegant, if slightly dubious solution would be for the OC to offer “free” installation to all owners, but pay for the installation out ot OC funds. Or find some way of categorising the upgrade as a fire safety provision.
But, to be honest, strata is full of illogical charges – like people on the ground floor having to contribute to lift maintenance or balcony repairs – so you could distibute the charges according to UEs and let the losers take you to the tribunal if they feel sufficiently aggrieved.