complex Pyomo MINLP to NEOS using Couenne.
So, I had to Google a bit to understand this part as I am not familiar with the package nor the NEOS service.
It would be beneficial as to where in the run-time progress you get the error message and what it exactly states.
From the NEOS webpage I found the following limitations
Retrieving results
If you are having trouble receiving results, you should read the NEOS Server FAQ section on results before contacting support. Jobs that exceed the 8 hour time limit or the 3 GB memory limit will not return results.
I am guessing your model doesn't run for 8 hours, but maybe you are hitting the 3 GB memory limit before a solution has been found?
Edit below, as a comment shed some new light for the reason to the time limit (or I misunderstood the question).
If you simply want a feasible solution (fast), then I would model the problem as a decision problem (see this answer on Comp Sci SE).
Shortly put and in general terms, you change the problem from something like:
\begin{align} \min&\quad f(x) \\
\text{s.t.} &\quad Ax = b \\
&\quad x \in \Bbb R\end{align}
to
\begin{align} \min&\quad 0 \\
\text{s.t.} &\quad Ax = b \\
&\quad f(x)\leq K\\
&\quad x \in \Bbb R\end{align}
where $K$ is a large constant you are fairly certain a feasible solution has an objective less than (or Integer.MAX_VALUE
or "large enough"). The problem should terminate as soon as a solution has been found.