Can't connect to public trackers - Private work fine

[calabash]

I run qBittorrent on Ubuntu (now on 13.10).  Everything has been working fine for years. 
Yesterday (13/11/13) I did a regular update as prompted by Ubuntu's update manager after which I can no longer connect to public trackers, although I can still connect to private trackers. 

I tried the same torrent (from http://eztv.it/ ) with Transmission (default client with Ubuntu) and the trackers connect and I can download with no problems.  I then tried with Deluge as it also uses libtorrent library (currently 0.16.11.0 as reported by both qBittorrent and Deluge) and it had no issues, the trackers connect and I'm downloading within seconds.

I did not make any config changes in qBittorrent.  I have a green light for port forwarding, I run require encryption (same settings in Deluge) but also tried with this off and still no go. 
I added the ppa for stable release and did an update but it says I am already on the latest version so ppa version must be the same as in the Ubuntu repositories at the moment. 

I also tried with both magnet links and torrent files.  Execution log just states that the link was added, no errors or anything about not being able to connect to trackers.

Update:  I noticed that the public trackers that wouldn't connect were all using UDP.  Just added a torrent which had a TCP tracker and it connects.  I went into Advanced options to see if there was something in there that would effect connectivity, for no particular reason I turned off the option "Resolve peer countries (GeoIP)" and immediately udp tracker connections started working.  How very odd as this had always been selected.  Perhaps it was just mere coincidence that as I clicked that option the connections happened?  I enabled it again and tried a new download - again with all udp trackers - and it now connects.  Mayhaps the disabling and reenabling of this option fixed a config glitch?  Anwya, all is back to normal so not sure what the issue was.