There is nothing to configure: installing the module is enough.

Before anything else, check the payment method
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

18.0 added the ``payment_method_type`` field (*Integration*) to
``pos.payment.method``, and core clears ``use_payment_terminal`` whenever it is
saved as *None required*. On **Point of Sale ‣ Configuration ‣ Payment
Methods**, the CashDro method must have:

* **Integration** = *Terminal*
* **Integrate with** = *Cashdro*
* the terminal host, user and password filled in

With *Integration* left at *None required* the terminal is not wired at all:
clicking the payment method just adds a plain cash line, and nothing is ever
sent to the drawer — no dialog, no error, no traffic.

On site
~~~~~~~

#. Open a PoS session, add a product and go to the payment screen.
#. Select the CashDro payment method. The payment line must show **0**, not the
   due amount (that one comes from ``pos_payment_method_cashdro_fix``).
#. The drawer must start the operation and ask for the amount.

If it still fails, the dialog now carries the reason instead of the generic
sentence, and the browser console has the full error under ``[CASHDRO]``. What
to expect:

``The CashDro payment method '...' has no terminal host configured.``
    The credentials did not reach the front end. Either the fields are empty on
    the payment method, or ``pos_payment_method_cashdro_fix`` is not installed.

``TypeError: Failed to fetch`` / ``NetworkError``
    The browser cannot reach ``cashdro_host``. Check the host and that the till
    is on the same network as the drawer. A PoS served over HTTPS also blocks a
    plain ``http://`` drawer as mixed content, which shows up here.

``The CashDro answered 401/403/500 ...``
    The drawer is reachable and answering: wrong user or password, or the
    CashDro3WS service is failing.

``The CashDro did not return an operation id: ...``
    The drawer refused ``startOperation``. Its own envelope is in the message —
    usually a busy drawer with an operation still open from a previous failure.

``The CashDro did not finish the operation in time.``
    ``startOperation`` was accepted but the drawer never reached the finished
    state within five minutes.

There are no automated tests: the flow needs a CashDro terminal answering on the
network, which is also why none of this is caught by the OCA CI.