Thermostat disconnecting

[Gareth-2]

I've had my new boiler and nest thermostat 4 months, since then the thermostat continually disconnects itself, so no heating, I have had a replacement thermostat about 2 months ago, same issue I'm afraid, it works for about a week then for no reason disconnects itself from the WiFi and I have to reconnect it, the thermostat is permanently mains connected, to assist the signal I've installed a Wifi booster approximately 5ft away from it but still the problem persists, this is not good as we are now coming up to winter and I can't trust the thing, any ideas or should I just give up and find a more reliable thermostat such as a Hive. 

[MartinJEvans]

Are you sure it is the WIFI it is disconnected from and not the heat link? I thought the thermostat still works if WIFI not connected (although not via nest web site and your phone) but obviously won't work if not connected to the heat link (which I belive uses Zigbee or something like that). Mine used to lose connection to the heat link all the time until I moved it a lot closer to the heat link.

[Gareth-2]

Hi Martin I thought that too but the BOXT engineer came he said that the link is fine and fitted a new thermostat but I still have the same issue 

[MartinJEvans]

Can you see the heat link? Does it have a green light on the front? I think you can ignore the other comment about C-wire as you said "the thermostat is permanently mains connected" which I took to mean you have connected it via a USB cable to a charger.

[Patrick_Caezza]

How do you have the Nest Learning Thermostat Wired?

Is there a C wire installed?

If you don't have a C wire, you should install one. There are a couple of ways to add a C wire, with the easiest being to use a spare thermostat wire if there is one. If one isn't available, the next easiest is to use the Google Nest Power Connector.

I know that Nest claims a C wire isn't required, but in the real world, you will need it sooner or later. The fact is every HVAC system out there is made differently, and the "Power Stealing." method that Nest uses to keep the batteries fully charged is hit or miss.