I am have exactly the same issue. i've tried opening the ports on my main router (WDR4900) but the TD-8816 is having none of it. I still see the ports being blocked externally. I've tried tweaking...

kuronie wrote Already discarded this firmware and switch into a factory converted to dd-wrt build. So much more stable. Can you actually get dd0ert on this box? If so How?

Updated with this BETA firmware seems alot more stable now, with no drop outs