new BT Business Smart Hub 3 - no Dynamic DNS service?

Ive just got a fibre into the house with BT. along with it came a BT Business Smart Hub 3
its status page tells me :
Connection External FTTX
App version 1.9.0
Firmware Version R1.21.0-R-910349-PROD-83002

I cannot seem to find anywhere within it a configuration for Dynamic DNS service... what am I doing wrong?

also it would be handy if I could assign certain of my private-side LAN devices to always use the same IP address, I used to be able to do this on ADSL broadband routers
and in the same area I used to be able to assign privateside devices their own friendly names and symbols. cannot seem to do that here either
Help!

Found a link to the user guide for that router, User Guide

It says Dynamic DNS

You can configure your Hub to use Dynamic DNS.
From the Hub Manager home page, go to - Advanced Settings > Broadband > Dynamic DNS

Then fill in the details for your Dynamic DNS service.

Select Save to store your changes.

Note: You'll need a Dynamic DNS service provider to use this feature. They'll give you all the details you need. Currently the Business Smart Hub 3 supports DynDNS, NoIP, ChangeIP, EasyDNS, Zoneedit and DNS-O-Matic.

Thanks for this but - no dice.
In that part of the menu system there are no Dynamic DNS fields. I have done this quite a bit before so I broadly know what Im looking for.
in the are of Advanced Settings > (prompt for admin password) > Broadband, I have 4 tabs:
Internet, VPN, Routing, DNS Hosts

see screenshots here

Just send a posting on a EE communinty forum saying the following regarding the firmware revision you have: DDNS isn't currently supported but the fact it was visible in the pre-upgrade build gives me hope it will return at some point. In the interim, if you need a DDNS solution, and there's a device on your network that's online 24/7, then you can probably use some client software to do the updates.

That quote was from Bob Pullen. It does seem mad that they are expecting you to run a device on your network to keep the DDNS up to date.