but as a general question what sort of things should i be looking at, or things that could help?

Without myself having done so, I suspect some network error (timeout?). So, something that could help - wrap your $session->trap calls into a block eval:

    my $result;
    eval {
        local $SIG{__DIE__};
        $result = $session->trap( -enterprise=>'.1.3.6.1.3.42',
            ...
        );
    }
    if($@) {
        warn "error calling \$session->trap(): $@\n";
    }
[download]

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