We are regularly experiencing strange issues with networking on our dedicated server. It runs Windows Server 2012 R2 x64 on Xeon E5620 with 16 GB RAM and Intel 82575EB network adapter.
Please note that we've already tuned
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters key values
MaxUserPort to 30 and 65530 respectively.
At a random point of time our websites stop responding, the reason being they cannot connect to a local database. It's approximately 2 weeks uptime when this issues start taking place. The system log starts getting TCPIP warnings 4227 and 4231.It states "A request to allocate an ephemeral port number from the global TCP port space has failed due to all such ports being in use.".
If I run
Get-Counter -Counter \TCPv4\*
Get-Counter -Counter \TCPv6\*
netstat -abn | find /c ":"
I always get reasonable value of 500-1500 connections, which is not even close to 65K limit.
Additionally, "localhost" stops resolving to ::1 locally, reverting to 127.0.0.1
Only a forced machine restart can resolve the situation.
Could it be a network adapter problem?
It happened again and seemed to have been resolved when I restarted the mail server. Weird though, all the counters showed ~1000 connections with ~500 being active at the moment, and still the 10055 socket error when trying to connect to the database which has nothing to do with the mail server.
UPDATE 2 This IS strange, but the daily restart of the mail services fixes the problem completely.