Do not allow PD/Address release option missing

[nevolex]

Hi cannot find, such option under wan settings for ipv6 and every time it reboots/ drops I get a new prefix

"Do not allow PD/Address release"
Prevents the operating system from sending a DHCPv6 release message on exit.
Some ISPs will release the allocated address or prefix when a client sends this message. With this option set, the client is more likely to receive the same allocation with subsequent requests.

is that no longer offered?
thank you

[Bob.Dig]

@nevolex It is in System/Advanced/Networking if you are on plus.