UPnP unreliability for Mac Transmission - false green lights

[Lord of the Rings]

Perhaps this is router brand or model issue, but I do have my doubts. A moderator from a private torrent site reported to me last December there's a high number of Transmission users who are firewalled. The issue is, in the Transmission settings/preferences under the Network tab section it can give the green light representing UPnP is working ("Port is Open") and is not firewalled. This is not necessarily the case. (One of the moderators who uses Transmission confirmed the same issue.)

As a result of the above, I need to either port forward or port trigger to make sure I am not firewalled according to the private torrent site's reporting. Transmission's lack of reliable UPnP has been an issue since I first started using it 3 and a half years ago. A year and a half ago I thought things had improved. But green lights do not necessarily mean all is as it should be. I personally use a belkin via ethernet. UPnP works fine with other p2p apps I use.

If you have had a lack of reports about this it is probably because most people use public trackers and are ignorant to the issue and those that use private torrents are probably unaware they are firewalled. Who is going to tell them? Some private torrent sites will list this detail on their personal records page along with their torrents they might be seeding, but some private torrent sites might not.

There are also some very easy tests on the web to verify whether the port is both TCP and UDP open or not, one of them I originally found via sourceforge I recommend elsewhere.