One possible reason is you may be using ETo weather algorithm and the returned data by ETo is now quite large and exceeds the storage allocated to it in your firmware. So the bottomline is your firmware 2.1.9(9) is outdated. If you are not ready to upgrade your firmware yet, you can try the following:
Download the API testing script:
https://openthings.freshdesk.com/support/solutions/articles/5000716363-os-api-documents
open it in a browser, put in your controller’s IP and device password, then choose Change Options (/co) API at the end. Type in option name:
uwt
and value
0
This will reset the weather algorithm to 0. After that, power cycle your controller (remove power and then plug in power again). That should fix the issue, if the issue is indeed caused by the weather data.
You can also use the script to save a copy of your configurations (the Get Json All /ja API). But in the end the only solution is to upgrade your firmware to the latest 2.2.1, which should solve this problem for good. Firmware update instructions are here:
https://openthings.freshdesk.com/support/solutions/articles/5000832310