Hi all, wanted to get your thoughts on how to best approach an issue with our bathroom and laundry vents not working very well. We have 2 bathrooms and 1 laundry in a relatively new unit (built post 2010) that doesn't have strong exhaust ventilation. I've attached images of the roof cavity and vent from the main bathroom, the setup looks the same for all three rooms.

None of the room have dedicated switches for ventilation, and all three vents have piping that lead to a larger pipe with a fan (pictured). It seems to be an always-on system with a fan that's simply too weak to do it's job at extracting much air from the rooms, and it gets weaker the further away (laundry/second bathroom are very weak and basically don't do anything at all).

What's the best solution here to resolve this issue? Should I look at a stronger fan to replace the one that's already there? This seems like the 'easiest' solution but I'm guessing it probably still won't be strong enough unless I find one that's very powerful, it also has the downside of being a single fan for all three areas rather than individual control (which is fine, but not ideal, as long as it works of course).

The alternative I was thinking about is installing individual extractor fans to replace the square vents in each area, but this would obviously be more costly, and we'd need an electrician to wire a new switch for each room, how much would something like this cost and is it feasible?

Bathroom & Laundry Exhaust Vents Not Working