I used to have a 'computer-controlled' hot water system (not wi-fi, I accept) and the remote controller head in that kept failing.
Investigations made by the manufacturer could not find what was causing the units to fail; but they suspected some form of interference in the area might be causing the problem (not that there were any large radar dishes, pylons etc. in the area).
The only way it was resolved (after about three failures/replacements) was that they brought out a new model of controller. So I strongly suspect that their original design might have been faulty.
So, thinking in terms of spurious radiations, is your microwave oven on the other side of the wall, or are there large pylons, radio transmitters or radars in the vicinity?