Lately one of my Windows 10 machines started to behave quite strange, after about a day of use, browsing Internet was no longer possible. I could still ping resources, but not use any browser or other application requiring Internet access. A reboot fixed the problem, and then after about a day, sometimes less, the same thing happened.
After some research / troubleshooting I found the following in the event log
Event 4231: A request to allocate an ephemeral port number from the global TCP port space has failed due to all such ports being in use.
The fix
After some additional research I came across some posts on similar issues for Windows Server 2012 R2, but not Windows 10. But I decided to try the same configuration that fixes the problem on Windows Server 2012 R2, and voila. it worked.
Note: Feature updates (version upgrades) to Windows 10 is sometimes removing these values, so after upgrade, check that they are still there.
Simply create the following registry info:
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
TcpTimedWaitDelay
REG_DWORD: 0000001e (hex)
MaxUserPort
REG_DWORD: 0000fffe (hex)
TcpNumConnections
REG_DWORD: 00fffffe (hex)
TcpMaxDataRetransmissions
REG_DWORD: 00000005 (hex)
Omg thank you!!! This was driving me insane!
Thanks man! You saved my Integration Tests 😀 😀 😀
Just wanted to say thank you for creating this article. I'm hopeful it will address my issue. The behavior you summarized aligns with what I was seeing. To expand on the behavior and my observations some, I could not access any IPv4 websites using my browser, but IPv6 sites would work (e.g. I could search in google, but not open a link unless it was cached). Using cmd, I could ping websites and domain names, but using my browser NO IPv4 domain names or ip addresses would work. For example, I could not even connect to my router/gateway by… Read more »