"Not Connectable" all of a sudden

[advance2048]

Hi,

I've been using uTorrent for a long, long while now - updating whenever a new version is available. I have been having no problems at all until a few months ago, when - all of a sudden - uTorrent alerted me of "No incoming connections" (Yellow icon). I haven't installed anything, and nothing changed in my router. Port forwarding was enabled, Windows Firewall had an exception, there was no other security package active or even installed for the matter... it didn't make sense. My last effort was to use the System Restore tool - which happily worked! I reverted a few days back, I think that perhaps removing a few Windows Update software updates - and I got the lovely Green icon.

Yesterday, the same problem appeared - again, but even worse. Now I get a "Not connectable" alert (Red icon). Nothing has been changed, and no Windows Update software update have been installed, as far as I know. (Auto-updated have been off). When I saw the problem, I thought it might be time to install these software updates, as they might fix it - but no. Anyhow, I am currently completely updated as far as Windows Update says, my AVG says it doesn't see any viruses and I have no adware or anything other installed.

I tried everything suggested in this topic: http://forum.utorrent.com/viewtopic.php?id=15992#p258233 (COMMON PROCEDURES THAT SHOULD BE FOLLOWED, REGARDLESS OF THE PROBLEM) but nothing worked.

I'm currently using uTorrent 1.8.1 on Windows XP SP3, patched with the latest updates available. Windows Firewall is enabled, and is the sole firewall. I removed the exception and re-added it - didn't help. The uTorrent port is currently configured as 39599, and there is a port forwarding rule on my router - a 3Com 3CRWER100-75 wireless router, for port 39599, both TCP and UDP. TCPIP.SYS is patched to allow 50 half-open TCP connections. I tried using UPnP, enabling it in the router and in uTorrent - UPnP port allocation didn't work, according to uTorrent's log. I tried updating the wireless router to the last, most recent version of software - didn't fix anything. Still, "Not Connectable" and the uTorrent port forwarding test fails.

I have a local port bind, as detailed by NETSTAT -B:

TCP mylocalpc:39599 mylocalpc:8140 TIME_WAIT 0

I've been running uTorrent like this for a day now. Downloads continue, in uninspiring speed, I assume caused by the outgoing connections only limitation. Not sure what to do next..

Can anyone help? Did anyone encounter this "all of a sudden uTorrent doesn't work" phenomenon?

[Ultima]

Hm. Do you have another computer to test?

[advance2048]

I do, and I will use it - but right now, I've left my computer running for about 10 days and went on vacation. I came back today, and it seems the computer rebooted a number of times, due to software updates. Anyhow, I started uTorrent and the icon was green - hurray!

However, now (15 minutes later) it is back to yellow. Not sure what is happening exactly... I'll check using a different PC.

Will update soon!

[Firon]

Yellow is merely indeterminate. Your best bet is to use the port tester in the Speed Guide and see what it says while the icon is yellow.

[advance2048]

I haven't had the time to properly test the situation - connect another PC and see what happens.

However, this morning I opened Wireshark and noticed that incoming and outgoing UDP packets on the uTorrent port are flowing freely, but TCP connections are absolutely not. I am not seeing any incoming TCP packets. (I even set the router to DMZ, still nothing. Not even from the port check site.) I have a few outgoing TCP packets that are attempting to form an outgoing connection (ACK packet), with my internet IP as destination and local network IP as source, and are immediately (i.e. 1ms after being sent) receiving a connection reset TCP packet (RST/ACK packet).

Why would uTorrent try and open a TCP connection between the local PC and the external IP?

[thelittlefire]

RST packets are traffic manipulation at work... from your ISP or any ISP in between you and your peers. Look up Sandvine.

[Firon]

µTorrent tries to connect to itself because the tracker usually returns your IP in the peerlist. It doesn't know it's you until it's connected to you.

Still, very strange. Have you tried connecting straight to the modem to see if the same issue happens?

[advance2048]

Okay, connected another PC and saw nothing of interest on the line. Then I figured out I was using a router, not a hub - duh!

Anyhow, I started fidgetting with the setup. I tried connecting another PC directly to the cable modem - it worked. I tried connecting my PC directly to the cable modem - didn't work. I resetted both and tried again - and it worked! Strange.

So, what I did next was double, triple check the settings in the router. Everything seemed right. I tried setting the DMZ to my PC - strange, it worked. Next, I removed the DMZ configuration and tried changing ports, opening both TCP and UDP, resetting - nothing worked. Finally, I reset the configuration to factory defaults and reconfigured everything from the start. Still, no success.

Finally, out of despair, I tried again something I tried a few weeks ago - disabling all of the port forwardings in the router, instead enabling UPnP, and enabling UPnP port mapping in uTorrent. What's this? A green light?!? Yes, it worked!!

Other programs that use UPnP port mapping, like eMule, still don't seem to work. However, at least uTorrent is finally accepting incoming connections!

Let's hope this lasts.