This is the most infuriating part. The best solution to these issues is to remove the need to move in the first place, and WFH for the people that want it and who can do it removes a huge amount of traffic with comparably little cost (company laptop, a screen and maybe a desk and chair, many of which could just be taken from the office).
What happens if the instance which hosts the community is down but other instances are online? I just made a post to a community on an instance that doesn’t exist anymore, but will other instances get that post, or is it reliant on the instance which hosts the community coming back online?