I've been using the BT Business Smart Hub 3 since August 2023 and it has always been lacking in features and buggy.
Because this was a newly released modem/router I stuck with it in the hope that firmware updates would cure the many issues but over 6 months later and reading the online forums, this router is plagued with problems.
I notice that I am now currently on:
Firmware version: r1.34.0-R-994210-PROD-83002r 1
This firmware version is still riddled with issues but here is the strange thing... DDNS disappeared from the firmware a while ago but my router is still updating my DDNS provider at every change despite the DDNS settings not being accessible in the settings. This is not a major problem at the moment but it will be if I ever need to change the settings.
I guess I was 'lucky' and setup my DDNS before the feature was pulled from the firmware but the fact that the router is still updating means that the feature must still be there.
Come on BT, this is a mess and not fit for market.
***UPDATE***
I gave up with the BT supplied Business Smart Hub 3 and purchased an ASUS RT-AX59U for just under £100.
Setting up the Asus was straightforward and demonstrates how bad and feature restricted the Business Smart Hub 3 is.
Firmware upgraded, DDNS and DHCP IP reservation setup along with all port forwarding rules for CCTV and various other servers in just over an hour.
Possibly the best time and money I have spent for a long time!
This is not the latest release router but it is perfect for my office. I do not need long range WiFi coverage and I went for an aesthetically pleasing unit with a small footprint and internal antennas. The router also has 3G/4G/5G tethering built in via the USB port so you do not need to use that silly BT Hybrid Connect thing at whatever cost it is these days. You can just plug your iPhone in to the router USB port in the event of your FTTP connection dropping, toggle the personal hotspot on your iPhone to on and you automatically switch over to mobile data and then switch back to FTTP again once your FTTP connection is working. I fully tested this feature and it is very stable and reliable.
For anybody else on BT Business FTTP who wants to go this route, the WAN settings that worked first time:
Set WAN connection type to PPPoE
Username=btbusinesshub@business.btclick.com
Password=none
...and leave everything else as default