Lost Remote access to wifi thermostat with new router

[#1]

I have had a Heatmiser wifi thermostat model PRT-TS WIFI working successfully for a couple of years using a Thomson router. I recently upgraded to fibre broadband and got a different router - a Sagemcom 2704n. I have not been able to set up the remote access to the thermostat as it does not appear in the routers list of connected devices and hence I cannot forward  port 80 to it.
I have changed the router allocated IP address range to 192.168.1.1 to 100 using the "expert" mode and given the thermostat an IP address outside this range of 192.168.1.200. I am able to communicate successfully with the thermostat from a WIFI enabled laptop on the local network using the IP address 192.168.1.200.
Can anyone suggest any reason for this problem or is it linked to the many issues identified for the Sagemcom 2704n router? Is it possible to forward a port to a specific IP address rather than a device?

[#2]

I have neither a Heatmiser stat or Sagemcom router and so offer this up as untested theory.... 😉
The absence of the stat in the connected devices list is presumably because the router has not yet 'seen' it insofar as seeing traffic to/from it. That said, you'd think that your laptop connecting to it would have at least required an ARP request to which the router would have captured the response. Anyway, is there anything you could do to get the stat to start talking - perhaps rebooting it, performing any connectivity tests from it if available etc - just so that the router can hopefully then see that it is alive and add it to the devices list?
You could also try plugging the laptop in to the router via Ethernet as the bridged connection might make it more likely that the router itself 'sees' the traffic between you rather than being fast-switched in a separate process within the wifi side of things.
It does seem a bit poor that you cannot forward to an IP address as whilst I can see the advantages (automatically accommodating dynamic allocations) there are also disadvantages too (e.g. NIC swaps mean re-configuration of port forwarding).

[#3]

Thanks MJN. I have rebooted the thermostat several times during my attempts to get it to work but I will try again. There appears to be no connectivity test with the thermostat.
Connecting my laptop to the router with an ethernet cable sounds interesting and I will definitely try that but it will be a few days as I am away at the moment.
I will will report back when done.
Note: the production of the connected devices list in the router is a bit flaky as refreshing the list several times can give different numbers of devices in the list each time. I've noticed that sometime the devices have a name and sometimes the same device is called "unknown".

[#4]

I have a Heatmiser PRT-TS WIFI thermostat that has been working OK for a few years with my Billion 8800NL. I have not tried to set it up with a 2704n but have one sitting in a cupboard somewhere if needed. If I get the chance over the holiday period I will try it out, I have a non standard firmware, think this is the thread http://community.plus.net/forum/index.php/topic,137629.0.html
Is the Thomson router the TG582n? If so then you might be able to use it on your fibre connection if you upgrade the firmware.
IIRC the latest firmware for my version of the 582n (with USB port) works for either ADSL or fibre.

[#5]

Surely the Billion router is better than the 2704n, and is VDSL capable, so would you not be better to use the Billion, and get rid of the Openreach modem?

[#6]

@Mustrum
I don't think the OP has a Billion, just the ADSL Thomson and the 2704n.
I got my Billion 8800NL when I got fibre and use it unless I need to try something out for a few days with an alternative device.

[#7]

Ah, sorry, misread who had what!
However the OP could continue to use his working modem with the OR modem.

[#8]

PeteB, I am not certain which Thomson router I have but I will check when I get home next week. Just looking at pictures of Thomson routers I think I have a TG585

[#9]

I carried out MJN's suggestion of connecting my laptop to the router with an ethernet cable to contact the thermostat to try and get the router to see the traffic between the 2 devices. I turned off the laptop wifi. I could communicate with the thermostat but the thermostat did not appear in the routers list of connected devices.
Strangely after I had done this the router showed no devices connected for a few minutes, despite repeated refreshing of the list, even though there were some and they were working.
My old router which did recognise the thermostat was a Thomson TG585v7. I don't think this is suitable for fibre.
I set up a new NowTV box via wifi and the router recognised it straight away.
It looks like I may have  to get another router if I want remote access to my thermostat unless PeteB comes up with something.

[#10]

Another idea; again based on theory alone...
You could try spoofing the stat with your laptop to see if you can get it in the devices list for forwarding to. To do this you would need to set the laptop's IP address to that of the stat and likewise the MAC address - this can usually be done via Device Manager under the Advanced settings page for the adapter.

[#11]

Well MJN your theory appears to have been successful but I have concerns about stability.
I changed the IP and Mac addresses of my laptop ethernet adapter to those of the thermostat. I plugged in the ethernet cable and went to the Port Forwarding section of the router, and in a list of devices there I found the ethernet adapter called "Unknown" followed by the Mac address. I forwarded the relevant ports to it then unplugged the ethernet cable, turned on the wireless and put the WAN IP address into a browser. Bingo, the thermostat page appeared. I logged in and out of the thermostat a few times but then it stopped working.
I checked the Port Forwarding details and saw that they had changed. Originally the details about the device I had forwarded to said:
Unknown "mac address" ( "mac address") where both mac addresses were the same.
Then the mac address in brackets changed to that of a NowTV box.
I deleted that entry and went through the procedure again. This time the devices list in the Port Forwarding section had the ethernet adapter called by my laptop's name. Contact with the thermostat was again successful via the WAN IP, and the next day it still works.
The device details I have forwarded ports to now says "laptop name" ("mac address")
While I was playing with the router yesterday the list of connected devices on the home page disappeared completely. Today it is back and lo and behold the the thermostat is there with the correct IP and mac address albeit called "Unkown". This was how it was in the Thomson V585 router.
It feels like the router is faulty or has very poor firmware. However we have made a big leap forward.
Thankyou

[#12]

Top marks for your persistence at any rate!
I think I'd be inclined to lean towards poor firmware. If there's a near-perfect example of things being made down to a cost - and the negative consequences this has - it has got to be consumer grade routers...

[#13]

The remote access to the Heatmiser thermostat worked for about a month then it failed. On examining the port forwarding configuration in the router I found that the device that the relevant  ports are forwarded to had changed automatically. I don't know what triggered this. The poor firmware in the router prevents me from keeping control of port forwarding.
Carrying out the spoofing procedure got everything working again but in the long term if this keeps happening I will be changing my router.

[#14]

I have had no problems with my Heatmiser thermostat and a Billion 8800NL.

[#15]

Hi, just seen this post and thought I would share my experience.

I have a sagemcom f@st 2704N router (adsl) from plusnet and a Nest thermostat (and co2 alarms). I could not for the life of me get the thermostat to connect to the wifi network (the SSID was the standard one from plusnet). After many many MANY hours of banging my head against the wall (changing password, going from 802.11b/g/n) I eventually found the problem to be with the SSID. I changed the SSID for a different one and below and behold everything worked in harmony! Maybe this could solve your problem as it did mine?