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.
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:
REG_DWORD: 0000001e (hex)
REG_DWORD: 0000fffe (hex)
REG_DWORD: 00fffffe (hex)
REG_DWORD: 00000005 (hex)