What I did so far to diagnose:
* Checked for broken cables. Nothing is broken. When I connect the wires between the thermostat and the boiler directly, the thermostat has no problem functioning.
* I (re-)installed the latest firmware, also after I used the diagnosis firmware temporarily (see further up ahead).
* I tested the power values, and all are within acceptable ranges. This testing procedure was used: http://otgw.tclcode.com/debugging.html#interface
* The test mentioned on the same page using the diagnosis firmware was performed (test #4). All timing values are 'OK'.
* I switched the polarity of the boiler and of the thermostat connections on the OTGW. Tested all four scenarios. None of the tested configurations made a difference.
* I enabled remote override support on the thermostat. This also did not make a difference.
A GitHub repository notes a configuration that is the same as mine (an OTGW, same boiler, same thermostat), which seems to work fine. This makes me suspect something might be wrong with my OTGW. For reference:
https://github.com/ebaauw/homebridge-otgw
If anyone has any ideas for further diagnosis, I would really appreciate if you could share them with me.
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