** Description changed:

  My network has both DHCPv6 and SLAAC for IPv6. From both a privacy
  perspective and readability reasons, DHCPv6 should *always* be preferred
  over SLAAC addresses when available.
  NetworkManager has always been able to adhere to that by simply setting
- ip6.privacy=0 for the connection.
+ ip6.privacy=0 for the connection. Then it would not generate temporary
+ addresses and use the DHCPv6 address as the source for outgoing traffic.
  So if you would - for instance - run `curl ifconfig.co`, the DHCPv6
- address would be used to connect to the outside world.
+ address would be used to connect to the outside world and be echoed
+ back.
  Since the update to 1.36.6, this is no longer the case. NetworkManager
  now routes outgoing traffic through the SLAAC address, even if
  ip6.privacy=0 is set for the connection. Setting
  net.ipv6.conf.all.use_tempaddr=0 and
  net.ipv6.conf.<interface>.use_tempaddr=0 with sysctl also no longer has
  any effect.
  Removing the SLAAC addresses with `ip addr del` or disabling SLAAC RA's
  altogether is the only way to stop NetworkManager from preferring SLAAC
  over DHCPv6 now.
  Looking at the changelog of NetworkManager 1.36.6, things regarding IP
  address order and temporary addresses have been changed in that release:
  When running `ip -6 a`, the list now sorts SLAAC addresses above DHCPv6
  addresses. With NetworkManager 1.36.4 this was not the case. (The Linux
  kernel uses the address highest in the list as preferred.)
  This can break many real-life use cases. For instance, my router gives
  out static leases to my machines. Those addresses are whitelisted in all
  kinds of firewalls to allow me to access servers for my work. Now that
  the "wrong" address is being preferred for outgoing traffic (a SLAAC
  address that I have no influence on), I am being locked out of the
  servers in question unless I forcefully remove the addresses or disable
  SLAAC on my router, so my outgoing traffic is being routed through the
  DHCPv6 address again.
  So this update introduces a very breaking change in IPv6 source address
  selection to an LTS release, while LTS releases should be stable.
  I should note that the bug is not present in NetworkManager 1.38.0 on
  Debian sid. That just prefers DHCPv6 addresses when available, like it
  PRETTY_NAME="Ubuntu 22.04 LTS"
  VERSION="22.04 LTS (Jammy Jellyfish)"
  nmcli -v:
  nmcli tool, version 1.36.6

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  NetworkManager 1.36.6 orders IPv6 addresses incorrectly

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