If you're able to connect via IPv4 to your network and Internet after you have this selected, try doing an update. If it works, go to the Network Connection panel and enable IPv6 as DHCP Automatic but leave IPv4 enabled. If you connection slows down and you try to get an update again, which then slows to a crawl, cancel the update.Then disable IPv6 again as "Ignore". I see this in a handful of cases every couple of months.