How to Configure a Technicolour 582n to make it compatible to existing network?

[#1]

So, here's the thing,
the village finally gets fibre, and BT plaster the roadside boxes to tell us.  "Great, at last, I'll upgrade" says I to myself.
Placed the order with Plus Net - supplier of choice since BT messed up the very first phone install. 
The Technicolor rolled up on time, the BT engineer didn't, and so the install happened when I was absent the site.

Now there is a working 582n that is by default on 192.168.1.254, and a default wifi setting - Working is good.
But the frustration sets in when attempting to go back to an IP address range that is compatible to all the other devices that exist here.
I can reconfigure it to the previous routers IP address on 192.168.0.1
I can reconfigure the wifi to the previous network name
but
It seems that the address range you can configure for DNS doesn't allow the full range of 192.168.0.1 to 192.168.0.254  and there are a number of devices which have, and need, a static address - stuff like the TVs, the NAS, the printer. 
Reading around the 'net it seems that telnet may provide a solution using a command line, but I haven't been able to locate a 'proper' manual or set of documentation for the device in the version that (seems to be) customised for Plus Net.
Does anyone have documentation, or a documented solution to this? 
I appreciate that its a cheap device, but this isn't a tricky requirement,

Anyone? 

ARW

[#2]

Home > Home Network > Interfaces > LocalNetwork http://192.168.1.254/cgi/b/intfs/_intf_/cfg/?be=0&l0=4&l1=2&name=LocalNetwork takes me to the page to configure the DHCP range.. using firmware 10.2.5.2FO

[#3]

The easiest way to change the routers dhcp pool address is to use backup / restore to backup the router setting. Then use notepad to edit the LAN IP addresses in the saved config file, save the edited file under a new name and restore the file to complete the changes.
Note: IMO port forward and UPnP doesn't work well with a static LAN IP in these routers. Best to use a dynamic IP address and tick "Always use the same IP address" in the routers network settings for each device.