BT SmartHub 2 keeps changing DMZ device IP

[alman]

I have a device that needs to be outside the DMZ,

However if I set the IP or Machine name in the DMZ ,  within an hours it changes to another IP address.

It sometimes chooses randomly a device that MUST not be outside on the DMZ.

I've tried it with the DHCP is disabled and enabled on the BT HomeHub.

But the result is the same.

The posts below explain the same problem but there is no solution

Solved: BT Business hub 2 - DMZ ip changing itself - BT Community

BT hub randomly reassigns DMZ - BT Community

[Keith_Beddoe]

@alman 

Welcome to this user forum for BT Retail phone and broadband customers.

Are you a business user?

[WSH]

Yes, I’d agree.

The only thing mine connects to is a second router, (a Draytek), set up as DMZ host but I have noticed that if I plug a laptop into the SH2 to directly configure it, it loves to switch to the laptop when it reboots.  This isn’t a problem when the laptop is disconnected, of course as that IP no longer exists and I’ve got used to checking it is on the correct IP for the Draytek before I leave it any way, but it is strange.

Be interesting to see if anyone has a solution/explanation.

[alman]

Not business user, I have a normal Halo 900 fibre account.

 The device in the DMZ never reboots, remains on 24hours a day 

Yes the SmartHub2 changes the IP address, like someone logged and changed it.

Nothing reboots, everything is left on, yet the configured IP in the DMZ changes.2

[licquorice]

Is the IP you are allocating outside of the DHCP range of the hub, regardless of whether DHCP is enabled or not?

[alman]

yes, the IP is within the range, although DHCP is off.

so I've enable the DHCP, although not authorititative ,  and set the range at the top end out of the way.

....shall see if that helps, and will report back

[licquorice]

It needs to be outside of the DHCP range, NOT within it.

Leave the range as default.

[WSH]

Ah, the flakey SH2 DHCP again.  I must admit that I'd assume it would make no difference if it was disabled.

[alman]

( since first posting I've been hit with the worst flu )

So I've tried a limited top end DHCP range, and that didnt work.

So will try default DHCP range and pushing this devices IP to somewhere below 40.

The thing is , this device is a stubborn thing and has no IP config, so am using PiHole DHCP to assign to less than 50 

[licquorice]

Hang on, so the device you are putting in the DMZ doesn't have a static IP address?