Improving Tuya Zigbee Valve Signal Range in Enclosed Boiler Setup

Hi. Surprising situation.I mounted a device on a pipe at the DHW valve,just below the CH boiler. ( a company of many pipes to and from the boiler).Boiler enclosed with plasterboard.Zigbee gateway at a distance of 4m, another router 3m. They have one brick wall on the way.When I open the inspection hatch (35x25cm) to the boiler, the range is immediately there.The hatch is a plasterboard in a frame of Al.Plugging a signal amplifier-extender into a socket 2m away without a wall on the way or a metre away,but with a wall does nothing.Even a repeater inside the enclosure does not help. I have made some kind of Faraday cage of plaster and non-ferrous metals there? Or these devices have less range than claimed.Here is the inside of the controller:
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Antenna:
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How to solve this? Cut up the antenna and add your own and put it outside?

You can try and solder in at least an SMA socket.

In those two vertical leads in the photo on the left?

The antenna is on a PCB flooded with white lacquer, with ZT3L printed underneath.

Yes yes, I meant precisely these points:
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That's where I solder in, cutting off the antenna on the board at the same time?

I have performed an action of yes:
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Unfortunately, it's worse.The device is not detectable, i.e. the connectivity has died.I checked if something is shorted, but it's unlikely to be:

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A cable of about 1m, terminated with an SMA socket, an 18dB or other weaker antenna and unfortunately nothing.
Where is the error? What else is there to check?

>>20341619
imho You should cut these taces marked on picture