TCP/IP has reached the security limit imposed on the number of concurrent TCP connect

[N!ck]

Do a jew bear.

The router from o2 can handle lots of connections just fine. It's likely that when you reboot the router, Windows closes all of the connections excess that are open from your PC and that's why it's fast again.

[peteyt]

Agreed.

Also for future reference, to use netstat in command prompt it's "netstat -b", or you can download the TCPView application from Microsoft for free.

I have tried TCPView and got this:

PnkBstrB.exe 1080 UDP peter-5a4b6efcc 45301 * *
PnkBstrA.exe 1772 UDP peter-5a4b6efcc 44301 * *
vsserv.exe 1484 UDP peter-5a4b6efcc 10000 * *
mDNSResponder.exe 1492 TCP peter-5a4b6efcc 5354 peter-5a4b6efcc 0 LISTENING
mDNSResponder.exe 1492 UDP peter-5a4b6efcc 5353 * *
jqs.exe 264 TCP peter-5a4b6efcc 5152 localhost 1060 CLOSE_WAIT
jqs.exe 264 TCP peter-5a4b6efcc 5152 peter-5a4b6efcc 0 LISTENING
mysqld-nt.exe 592 TCP peter-5a4b6efcc 3306 peter-5a4b6efcc 0 LISTENING
fbserver.exe 3336 TCP peter-5a4b6efcc 3050 peter-5a4b6efcc 0 LISTENING
svchost.exe 1896 TCP peter-5a4b6efcc 2869 peter-5a4b6efcc 0 LISTENING
svchost.exe 1896 UDP peter-5a4b6efcc 1900 * *
svchost.exe 1896 UDP peter-5a4b6efcc 1900 * *
[System Process] 0 TCP peter-5a4b6efcc 1708 wy-in-f102.1e100.net:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1705 a92-123-153-66.deploy.akamaitechnologies.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1704 a92-123-153-66.deploy.akamaitechnologies.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1696 a92-123-153-58.deploy.akamaitechnologies.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1695 a92-123-153-58.deploy.akamaitechnologies.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1693 a92-123-153-66.deploy.akamaitechnologies.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1686 a92-123-153-40.deploy.akamaitechnologies.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1685 a92-123-153-40.deploy.akamaitechnologies.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1684 a92-123-153-40.deploy.akamaitechnologies.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1683 a92-123-153-40.deploy.akamaitechnologies.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1682 a92-123-153-58.deploy.akamaitechnologies.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1681 a92-123-153-58.deploy.akamaitechnologies.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1606 api-11-04-snc4.facebook.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1603 api-11-04-snc4.facebook.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1602 api-11-04-snc4.facebook.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1596 api-11-04-snc4.facebook.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1583 www-13-02-ash2.facebook.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1582 www-13-02-ash2.facebook.com:http http TIME_WAIT
firefox.exe 2448 TCP peter-5a4b6efcc 1563 channel5-02-07-snc1.facebook.com http ESTABLISHED 3 4,174 3 453 1,392 1
[System Process] 0 TCP peter-5a4b6efcc 1554 www-13-02-ash2.facebook.com:http http TIME_WAIT
[System Process] 0 TCP peter-5a4b6efcc 1552 a92-123-153-66.deploy.akamaitechnologies.com:http http TIME_WAIT
firefox.exe 2448 TCP peter-5a4b6efcc 1421 channel5-02-07-snc1.facebook.com http ESTABLISHED 2 2,784 2 302
msnmsgr.exe 2808 TCP peter-5a4b6efcc 1367 94-193-254-140.zone7.bethere.co.uk 59604 ESTABLISHED
msnmsgr.exe 2808 TCP peter-5a4b6efcc 1247 92.16.123.228 29750 ESTABLISHED
wlcomm.exe 2532 UDP peter-5a4b6efcc 1125 * *
msnmsgr.exe 2808 TCP peter-5a4b6efcc 1094 localhost 1091 ESTABLISHED 1 16
msnmsgr.exe 2808 TCP peter-5a4b6efcc 1091 localhost 1094 ESTABLISHED 1 16
msnmsgr.exe 2808 TCP peter-5a4b6efcc 1091 peter-5a4b6efcc 0 LISTENING
msnmsgr.exe 2808 TCP peter-5a4b6efcc 1086 by2msg4020215.phx.gbl 1863 ESTABLISHED 1 5 7 6,461
msnmsgr.exe 2808 UDP peter-5a4b6efcc 1083 * *
firefox.exe 2448 TCP peter-5a4b6efcc 1078 localhost 1077 ESTABLISHED
firefox.exe 2448 TCP peter-5a4b6efcc 1077 localhost 1078 ESTABLISHED
firefox.exe 2448 TCP peter-5a4b6efcc 1077 peter-5a4b6efcc 0 LISTENING
firefox.exe 2448 TCP peter-5a4b6efcc 1052 localhost 1051 ESTABLISHED 90 90 1 1
firefox.exe 2448 TCP peter-5a4b6efcc 1051 localhost 1052 ESTABLISHED 90 90 1 1
firefox.exe 2448 TCP peter-5a4b6efcc 1051 peter-5a4b6efcc 0 LISTENING
svchost.exe 1584 UDP peter-5a4b6efcc 1035 * *
alg.exe 1360 TCP peter-5a4b6efcc 1029 peter-5a4b6efcc 0 LISTENING
mDNSResponder.exe 1492 UDP peter-5a4b6efcc 1025 * *
System 4 TCP peter-5a4b6efcc microsoft-ds peter-5a4b6efcc 0 LISTENING
System 4 UDP peter-5a4b6efcc microsoft-ds * *
System 4 TCP peter-5a4b6efcc netbios-ssn peter-5a4b6efcc 0 LISTENING
System 4 UDP peter-5a4b6efcc netbios-dgm * * 1 201 1
System 4 UDP peter-5a4b6efcc netbios-ns * * 7 350 7 300
svchost.exe 1340 TCP peter-5a4b6efcc epmap peter-5a4b6efcc 0 LISTENING
svchost.exe 1584 UDP peter-5a4b6efcc ntp * *
svchost.exe 1584 UDP peter-5a4b6efcc ntp * *
msnmsgr.exe 2808 UDP peter-5a4b6efcc discard * *

[peteyt]

I figured out what was causing the problem. A bit ago I'd noticed a downloader.exe in my process - a google search said it could be a virus disguised as a system file or an actual system file. It was classed as a system file and was actually part of the Bitdefender Total Security 2011 Beta - I had thought maybe its that causing the problem as its beta - but needed to check first. It had quite a few connections when the problem occured and now i've uninstalled the beta - didn't realise the full one was out, the problem doesn't occur. Thanks everyone.