I'm writing this using a 3G connection on my phone.
At lunch time yesterday, the ports above and a few additional other ports like 40001 and 4089 stopped working on my internet connection at work.
SSH access still works and MySQL connections too I believe.
Using Wireshark on a Windows 7 laptop I can see loads of [TCP Retransmission] requests on the ports which don't work.
We have a Ethernet from our laptops (Windows, Mac and Linux) connected to a switch connected to a Draytek router connected to an ADSL line.
As far as I know there is no firewall turned on, on the router.
Ask if you need any more info, but how do I go about debugging this problem. Our ISP can't see any problems on the line.
EDIT: we've tried two completely different brand routers with no difference in what we observe. I can SSH out on a non-standard port and view my http requests being unsuccessfully ACK'd. Skype works fine BTW, just in case anyone was wondering.