Port will not open

[Dresnaw]

New here and following Transmission Help steps. I have used Transmission for several years, no major problem. All of a sudden it stopped working, no obvious reason. I discovered the port was closed and, no matter what I did, I could not get the port to open. I rebooted my OSX El Capitan desktop, rebooted my D-Link DIR815 router, made sure the necessary port forwarding on the router was done, even trying different ports. I disabled my Avast shields. I then followed these steps:

1. If you are still having problems, open the Message Log (in the Window menu) and post the debug output on the support forums.
Pause your torrents
2. Clear the log and set it to 'Debug'
3. Toggle "Automatically map port" in Network Preferences
4. Post the resultant output

When I opened the log it was blank. Here is the answer to number 4:

2016-12-01 22:03:17 +0000 port-forwarding.c:180 [Info] Port Forwarding: Stopped
2016-12-01 22:03:19 +0000 natpmp.c:70 [Info] Port Forwarding (NAT-PMP): initnatpmp succeeded (0)
2016-12-01 22:03:19 +0000 natpmp.c:70 [Info] Port Forwarding (NAT-PMP): sendpublicaddressrequest succeeded (2)
2016-12-01 22:03:19 +0000 upnp.c:239 [Debug] Port Forwarding (UPnP): UPNP_GetValidIGD failed (errno 0 - Undefined error: 0)
2016-12-01 22:03:19 +0000 upnp.c:242 [Debug] Port Forwarding (UPnP): If your router supports UPnP, please make sure UPnP is enabled!
2016-12-01 22:03:19 +0000 port-forwarding.c:92 [Info] Port Forwarding: State changed from "Not forwarded" to "Starting"
2016-12-01 22:03:27 +0000 natpmp.c:75 [Debug] Port Forwarding (NAT-PMP): readnatpmpresponseorretry failed. Natpmp returned -7 (the gateway does not support nat-pmp); errno is 61 (Connection refused)
2016-12-01 22:03:27 +0000 port-forwarding.c:92 [Info] Port Forwarding: State changed from "Starting" to "???"

I would have posted the respective logs but txt and pdf formats were both rejected, to my surprise.

Your advice would be appreciated. Thank you.

[Dresnaw]

Further information. I am downloading some data via Transmission but slower than I would normally get and in spite of the fact it tells me its port is closed. I have since installed BitTorrent client and it too tells me its port is closed. My router UPnP is enabled.

[Dresnaw]

]Is it your network?
I was able to download a document from Ubantu speedily.

Is your tracker responding?
The files having doownload problems show the trackers are not being connected to or that the connection has failed.

Are there too many (or not enough) seeders?
There is indeed a total lack of seeders with many files. I would expect no downloads because of that except that the tracker showed many seeders at the time of commencement and, of course, I cannot get the port to open.

Is it your speed limits?
My speed limits are set high for the high bandwidth I enjoy. It has never been a problem.

Is it a small swarm?
Yes, for the multiple files I am having trouble with. But for the lack of an closed port I would accept it as the cause of any problems.

Are you uploading too fast?
Uploading limit is 10kbs whereas download limit is 5000kbs. Normal capacity on my cable is 30Mbs.

Is it your ISP?
My ISP is excellent. I am sure it is not them. Glasnost test would not work.

Is it an old version of Transmission?
Test says latest version.

Is it your router or firewall making your "port closed"?
I have configured my router to have open and designated ports for Transmission. This may be an issue (have I configured it correctly) but it used to show the port designated as open until now. I have read much and played much but no luck opening the port. My OSX firewall is set to off.

Is it a Transmission Bug?
I doubt it. I have something set wrong. My BitTorrent client shows a closed port also.

[wfiveash]

I have seen a problem in the past where the method that transmission uses to determine that its listening port was open on the NAT router and being forward properly was not working. I don't remember the details but I think it uses some system on the Internet to do this and if that system isn't working then transmission will not indicate that the port is open. Note, I could be wrong about this so it would be good if someone could say how transmission checks the port.

[wfiveash]

Let me amend what I wrote above in that when I configure transmission to use a fixed (non-random) port, turn off UPnP and manually configure the router to forward that port to the system hosting transmission then the transmission indicates the port is open. This is odd because my previous config had transmission using a random port on launch with UPnP enabled and I would find the port was open. I have no idea why the port isn't open now and because the linksys router I'm using does not provide detailed diagnostics I do not know where the problem lies. Next up, installing dd-wrt on the linksys. 8^/

[wfiveash]

I just read a post on the linksys support forum where someone was having trouble getting UPnP port forwarding working and the suggestion was to backup then reload the router config (which reboots the router). I just tried that and now UPnP port forwarding to transmission is working so maybe that is something to try if you are using a linksys router.