Confused plus.net newbie (router query)

[#1]

Use the reset button on the NAS device. Job done

[#2]

...and you can absolutely guarantee that will not risk the data he has on the NAS already?

[#3]

I be surprised that it will format the disk. Other setting will be lost as it will revert to factory settings.

[#4]

I'd be very surprised as well, but not knowing the NAS box I'd be wary of giving such advice.
Undoubtedly what you've suggested is technically the best solution, but as long as he gets things working I don't think that would bother the OP. That's why to me the safest advice would be to give the step by step instructions on changing the router IP and DHCP settings as he requested.

[#5]

Thanks for the heads up Jelv, not sure how I missed that 
Right - Click 'Home Network' in the menu on the left and select 'interfaces'. Then choose 'Local Network' from the middle section. Once that's loaded click 'Configure' in the top right.
Once on this screen, you should see an option to edit an IP block that looks like: "192.168.1.254/24" - click edit next to this and change the numbers to "192.168.0.1/24" then click  Apply.
IMPORTANT - doing this will change the address you need to go to to access the router's setup pages (in case you have this bookmarked) to 192.168.0.1 - if you can't get to the setup pages after clicking apply, that will be why. That should however ensure that everything connected is issued an IP in the range of 192.168.0.* instead of 192.168.1.* which should solve the problem.

[#6]

Matt
I decided to follow your instructions on my Speedtouch 716 as I was not sure whether it would work as per your instructions as you did not mention anything about the DHCP pool.
It did not work as the DHCP pool was still issuing IP's in the 192.168.1.x subnet. In the end I had to give my PC a static IP address in the 192.168.0.x subnet but with the gateway of 192.168.1.254 as this was the gateway specified by the DHCP pool. So if the Thomson Router used by the OP has similar settings then it will not work.
The speedtouch 716 DHCP Pool has default settings of address range 192.168.1.64 to 192.168.1.253 with Gateway at 192.168.1.254. This allow addresses below 64 to be used statically by other devices. Static addresses have to be outside the pool. Therefore if the OP want to solve the problem at the thomson end then the DHCP pool need to be changed to:
DHCP range 192.168.0.131 to 192.168.0.253 Gateway =192.168.0.254

[#7]

I am not sure whether another IP range can be added at the Address/mask i.e. add 192.168.1.254/24 and leave the DHCP Pool as is. Does the Thomson bridge the 2 subnets?

[#8]

Further to this, I actually lost this thread somewhere, assumed it was deleted because of my stupidity!!
For anyone else who has this problem, the solution I performed:
Plugged NAS directly into the PC no router involved. Restarted both, and NAS got a new IP assigned to it - job done.
There is NO hard reset button, but a function button which if pressed in combination with pressing 2 other buttons and touching your nose, resets it (with no loss of data).
Thanks for all the replies and sorry I didn't reply sooner, as I said the thread seemed to dissapear.