There is an open fault ticket for the mobile network 22291125 for loss of multiple sites across NSW due to severe storms/high winds/heavy rains.
It mentions a Kingsgrove site was down and has been running on a generator for about a week.
Whilst this specifies for home phone and broadband services, Campsie isn't list here, it's pretty much due to the same reason.
Overall, Optus technicians are definitely aware of the issues and are doing their best to restore power as soon as possible. Thanks for your patience.