Problems connecting to NAS with new fibre Technicolor router

[#1]

I've just upgraded to Fibre and have plugged in the Plus.net supplied technicolor router in place of my old, rather crummy Netgear.
The router has so far recognised everything - Wii, mobile, several laptops - with one massive omission.  It is stubbornly refusing to acknowledge the existence of my Synology NAS which is connected directly to it by the supplied ethernet cable.
Given I've got 3TB of disk space on the NAS and several laptops in the house, this is a bit of a problem.  I've tried changing cables and I've tried changing the port that the router is plugged in to, all for no avail.  The router itself is recognising that there's an ethernet cable plugged in, and the router is happy to report that too.  But that's as far as I get.  The NAS worked perfectly before so I'm now completely stuck.
Any thoughts?

[#2]

I asked a similar question recently and the answer I got was that the drives have to be FAT32 format.

[#3]

@PasPer2 - I think that's only if you're plugging a drive into the USB port on the router, but as a NAS connects via ethernet, that won't be part of this issue.
I had the same problem with my D-Link NAS recently due to leaving it forced to gigabit speeds, then connecting it to a non-gigabit router... After a bit of head scratching, I ended up just resetting the NAS via the reset button. This was probably a problem unique to me and my ropey memory, but it could be worth a shot...

[#4]

Is the NAS set up with a static IP address on a different subnet to the one used by the new router? (e.g. you've manually set the NAS to use 192.168.0.1 but the new router is using 192.168.1.x addresses)
All of my Netgear routers default to 192.168.0.x whereas the Plusnet router uses 192.168.1.x.

[#5]

dfunked - my first instinct, after many years of doing anything computer related is always to turn it off and on again.  It's amazing how often it works   Sadly it didn't in this case
CX - I'll have to check when I get home this evening but I'm going to put good money on this being the problem.  I'd completely forgotten I'd given it a static IP address - certainly the old Netgear router dished out everything in the 192.168.0.* range as well.  That's this evenings task set then!
Many thanks for everyone's replies - we'll see what happens when I get home!

[#6]

Took me until this evening to sort it out, but yes, that was the problem.  All solved now,  Phew.

[#7]

Quote from: andrewbowden

dfunked - my first instinct, after many years of doing anything computer related is always to turn it off and on again.  It's amazing how often it works   Sadly it didn't in this case

By reset, I meant use the button on it to restore to factory settings, not to restart it... Would've probably knocked it back to using DHCP, so would have fixed the problem for you in a roundabout kind of way...