just assume they considered your suggestion and ask as if they did and must indeed have a reason why it didn't work: "so what was the issue with using sshd?"

just assume they considered your suggestion and ask as if they did and must indeed have a reason why it didn't work: "so what was the issue with using sshd?" you're assuming competence, and if they say "oh I never thought of that" then you can prompt them to consider it - "might be worth a shot" or something like that. Comes across less accusative I think.