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DHCP Reservation bug - BT Smart Hub 2

Nick-P — Sun, 18 Oct 2026 23:08:30 GMT

After setting “Always use this IP address” to YES, the Hub reports that a DHCP reservation has been saved, displaying the green “Changes saved” confirmation. However, after leaving and reopening the device’s settings page, “Always use this IP address” reverts to NO.

For clarity, I am only trying to reserve the IP already assigned by the Hub through DHCP, as confirmed by the Wireshark packet capture in the video below.

Video: Link to follow in a reply, in case it triggers the spam filter.

How to Reproduce
1. Ensure the device’s IP assignment is set to Automatic (DHCP) on the device itself.
2. Open 192.168.1.254 in a web browser.
3. Go to Advanced settings, enter the Hub’s admin password, then select My network.
4. Select the device from the list.
5. Set “Always use this IP address” to YES.
6. Wait for “Changes need to be saved”, then click Save.
7. The Hub displays the green “Changes saved” message.
8. Leave the device’s settings page, then reopen it. The setting has reverted to NO.

Specific Examples
Example 1 - Brother DCP-L2620DW printer (brand new - purchased 2026)
A brand-new printer, purchased in 2026, was unboxed and connected to a friend's network using WPS:
On the printer: Menu → Network → WLAN(Wi-Fi) → WPS/PushButton.
On the Hub: press the WPS button.
After the printer connected, I followed the reproduction steps above. The reservation setting reverted to NO after saving.

Example 2 - Windows 11 Pro
Tested on a physical PC using an Intel I226-V Ethernet adapter, with the original network adapter disconnected.
IP assignment was set to Automatic (DHCP) under:
Settings → Network & internet → Ethernet → IP assignment
The PC received 192.168.1.174 from the Hub at 192.168.1.254. Following the same reproduction steps produced the same result.
See the video linked above.

Example 3 - Newly created Linux Virtual Machine
Tested with a newly created Linux VM in virt-manager/QEMU/KVM, using DHCP and an automatically generated, persistent MAC address.
Following the same reproduction steps again caused the setting to revert to NO.

Additional Logs/Troubleshooting
For the Windows 11 Pro test, I used Wireshark to capture the complete DHCP Discover → Offer → Request → ACK exchange. This provides evidence that the PC obtains its address through DHCP.
I also recorded a video showing the configuration process, the successful save confirmation and the setting reverting afterwards. The video includes the Hub’s settings.
I work in IT and have reproduced this behaviour on two separate Smart Hub 2 units at different properties in different cities. The Brother printer example was at a friend’s house; the other tests were on my own Hub.

Workaround
Setting an unused static IP address directly on the printer, outside the Hub’s default DHCP pool (for example, within 192.168.1.1 - 192.168.1.63), works.
However, this requires additional manual configuration on the printer. The Hub’s reservation feature should retain the setting when it reports that the change has been saved.

Re: DHCP Reservation bug - BT Smart Hub 2

Crimliar — Mon, 19 Oct 2026 15:42:31 GMT

Not using an SH2 I can't verify the error, but it's not uncommon to have to reboot both the router and reboot/power-cycle the device for such settings to stick.

You also need to ensure that any devices you want to have static IP addresses, don't "rotate" (it's a security feature) their MAC addresses (set on device not router).

*Most of my equipment identifies itself by "host name" rather then IP address, but I believe this is not something the SH2 is particularly good at - could well be wrong!

Re: DHCP Reservation bug - BT Smart Hub 2

WSH — Mon, 19 Oct 2026 19:36:48 GMT

@Nick-P I’ve not been able to reproduce the fault, however….

Sitting pondering it, the SH2 is notorious for not releasing IP addresses properly and eventually running out of address space. The only way to clear is a factory reset.

I wonder if that is what’s going on here. That is, it’s struggling for address space and so refusing to accept the reservation.

(As I said before, static addressing is far more reliable, even if it does involve getting out of your chair to set it).

Re: DHCP Reservation bug - BT Smart Hub 2

Nick-P — Mon, 19 Oct 2026 20:27:25 GMT

Hi Crimliar,

Good shout - I have checked for MAC rotation, but unfortunately it doesn't appear to be the cause. In both Windows and Linux, the MAC address was unchanged after several restarts and always matched the Hub’s entry.

However this did peak my interest as was worried I overlooked something:

For Linux devices using Network Manager, the documented Ethernet default is "preserve" unless overridden. The manual defines this as “not to touch the MAC address on activation”.
https://www.networkmanager.dev/docs/api/latest/nm-settings-nmcli.html

I do know assumptions can be dangerous, so checking this, no overrides were present.

Under Windows, Microsoft only appears to document its “Random hardware addresses” settings for Wi-Fi. My Windows test used Ethernet.
https://support.microsoft.com/en-us/windows/experience/connectivity-networking/connect-to-a-wi-fi-network-in-windows

And for the printer, I can't easily check, but I'm almost certain a printer manufacturer would have to be extremely silly to enable MAC rotation (even for WiFi).

Even my Android phone uses 'persistent randomisation' by default. In other words, it keeps the same MAC for each Wi-Fi network until a factory reset. (Non-persistent randomisation requires extra configuration).
https://source.android.com/docs/core/connect/wifi-mac-randomization-behavior#persistent-randomization

Apple I believe is a bit more nuanced, but is outside the scope of this post.

I would be good to find an explicit resolution to the Hub's DHCP reservation rather than resign to a workaround. For example, not all printer menus are made equal and it's not always trivial to set a static IP on a printer (especially over the phone). One should be able to press the WPS button, then with a few clicks, permanently reserve the IP address obtained from the Hub's DHCP server.

Kind regards,
Nick

Re: DHCP Reservation bug - BT Smart Hub 2

Nick-P — Mon, 19 Oct 2026 20:33:56 GMT

WSH,

That is also a good shout, especially as I use a lot of VMs which I always configure so they get an IP on the Hub's physical network.

I will try factory resetting the Hub and report back.

Re: DHCP Reservation bug - BT Smart Hub 2

WSH — Mon, 19 Oct 2026 20:42:18 GMT

Yes. I also mentioned MAC randomisation in the previous thread.