Servers Struggling to Fetch DHCPv6 Leases

I have a number of servers, and I recently started reconfiguring my network for support IPv6. I’ve made IPv6 a requirement on all my servers, and have set static DHCPv6 leases for them, rather than manual configuration, as it makes it easier to manage their addresses.
However, most of the systems now take an unbelievably long time to connect, as they spend a lot of time waiting for the IPv6 configuration to complete.
I’ve even had some servers, occasionally, give up, and fail to come online until rebooted.

Does anyone have an explanation for what the heck is happening?
All the severs in question use bonded connections, and it seems to mostly affect the older ones, likely as they’re just slower, though I suppose it could be the older network interfaces.
I really don’t know, but I just spent 20 minutes fixing one that didn’t want to come up, and this is unacceptable.

Side note: This doesn’t strictly affect Fedora. I have a couple systems running Rocky Linux, and they’re affected as well.