port is closed but downloading works!

[litsan]

I continue to have the same problem: when using an external port check, says my port is open, but on Transmission 2.20b3, it says port is closed.

I run an Airport Extreme and use an Airport Express to extend my network. I've done all my port forwarding and firewall settings to no avail and the port continues to be closed in Transmission (btw, my torrent site requires that I use v2.20b3 also). Separately, my Torrent site blows hot and cold telling me I'm connectable at times and not connectable at most other times. This is exasperating, please help.

Thanks,
Lit

I attach the portlog:
2011-02-18 21:39:22 +0800 port-forwarding.c:183 [Info] Port Forwarding: Stopped
2011-02-18 21:39:22 +0800 natpmp.c:70 [Info] Port Forwarding (NAT-PMP): sendnewportmappingrequest succeeded (12)
2011-02-18 21:39:22 +0800 port-forwarding.c:95 [Info] Port Forwarding: State changed from "Forwarded" to "Stopping"
2011-02-18 21:39:31 +0800 natpmp.c:70 [Info] Port Forwarding (NAT-PMP): initnatpmp succeeded (0)
2011-02-18 21:39:31 +0800 natpmp.c:70 [Info] Port Forwarding (NAT-PMP): sendpublicaddressrequest succeeded (2)
2011-02-18 21:39:31 +0800 upnp.c:105 [Debug] Port Forwarding (UPnP): upnpDiscover failed (errno 2 - No such file or directory)
2011-02-18 21:39:31 +0800 upnp.c:125 [Debug] Port Forwarding (UPnP): UPNP_GetValidIGD failed (errno 0 - Unknown error: 0)
2011-02-18 21:39:31 +0800 upnp.c:128 [Debug] Port Forwarding (UPnP): If your router supports UPnP, please make sure UPnP is enabled!
2011-02-18 21:39:31 +0800 port-forwarding.c:95 [Info] Port Forwarding: State changed from "Not forwarded" to "Starting"
2011-02-18 21:39:39 +0800 natpmp.c:70 [Info] Port Forwarding (NAT-PMP): readnatpmpresponseorretry succeeded (0)
2011-02-18 21:39:39 +0800 natpmp.c:138 [Info] Port Forwarding (NAT-PMP): Found public address "218.212.110.34"
2011-02-18 21:39:39 +0800 natpmp.c:70 [Info] Port Forwarding (NAT-PMP): sendnewportmappingrequest succeeded (12)
2011-02-18 21:39:39 +0800 natpmp.c:70 [Info] Port Forwarding (NAT-PMP): readnatpmpresponseorretry succeeded (0)
2011-02-18 21:39:39 +0800 natpmp.c:218 [Info] Port Forwarding (NAT-PMP): Port 52025 forwarded successfully
2011-02-18 21:39:39 +0800 port-forwarding.c:95 [Info] Port Forwarding: State changed from "Starting" to "Forwarded"

[garrych]

I run an Airport Extreme and use an Airport Express to extend my network.

Is it "double-nat" situation? Give some more details about your network setup: like work-modes for both airports, their ip-addresses, wan mode etc...