> If your ISP assigns you dynamic prefixes (mine does), you can end up with devices not being able to connect to the internet after the router/modem reboots, since they're not told about the new prefix you just got from your ISP and happily keeps using the old one.

You have a broken router setup, it's not doing router advertisement. Every reply of yours in this thread is just you complaining about something that you misconfigured on your router or did not bother reading about in any decent IPv6 introduction. Please stop the FUD.