Do Toa lose access to collected masks if they are too far away?
I think the question is would Toa lose access to collected masks if they are outside of the MU which their suva are in?
3a)Can Toa who have a Suva access it when outside the MU?
3) The GBs built the Suva, and no, you cannot access them from outside the MU. The Toa would need to relocate them to use them now.
That's from 2010. The same principle still applies here IMO. The Nuva were outside the MU during 2006. The Suva were inside. No worky.
On Mata Nui, both Toa and Suva were outside, so they worked. If the Toa relocated the Suva outside now, they would work.
So that means that there is a shield in the robot hull that prevents Suva signals from getting through. And we are getting off topic. But hopefully that should answer the question.
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It's possible that being without Suva on Voya Nui might have contributed to the Nuva's weakness.