I think I understand why: your wto, which currently has:
is quite long. Firmware 2.1.8(4) assumed that wto is no longer than 60 characters: back then we didn’t have ET algorithm so it never came up that wto could be longer than that; also, the UI should not have saved the h, t, r, bh, bt, br parameters as those are irrelevant to ET (those are parameters for Zimmerman). In any case, as a result of the combination of these, when the firmware loads wto, some parts of wto is cut off, causing the query to fail.
Here is the work-around: first select ‘Auto Rain Delay’ as the adjustment method, set any delay duration you want, submit. Then go back and select ET as the adjustment method, choose baseline ETo, submit again. This should force wto to get rid of the extra parameters that it doesn’t need, and the resulting wto should fit in 60 characters.
We have addressed this issue in the upcoming firmware 2.1.9 which allows much longer wto string, but also we’ve modified the weather script to avoid saving parameters not needed by each specific adjustment method.