We suffer from a connection refused problem when the users of our web site try to open it. This problem happens in a random manner, about once or twice a month, and problem continues for a few hours. Also when happening, almost all connections are rejected by connection refused error. but there are successful connections meanwhile.
- OS: Win 2012 R2 Standard hosted on ESXI 6
- IIS 8.5
- Web server is hosting an ASP.NET application.
- Windows Firewall is on.
- Average current connection on server: ~3500 (based on Web Service\Current connection performance monitor counter)
- Total RAM: 40GB
- CPU: 30 cores, 2.30 GHz
There is plenty of RAM (more than ~60%) and CPU (more than ~70%) available while this problem happens. Also we checked the network firewall and apparently traffic is passing through network firewall without problem and problem happens at the server level. And we can not even open the web site by doing Remote desktop and trying to open in locally.
We checked about exhausted port problem and it seems that is not the problem. The number of SYN packets are high, but its similar to other days when everything is fine.
This is one day summery of HTTPERR log:
s-reason COUNT(ALL *) Timer_ConnectionIdle 462040 Timer_MinBytesPerSecond 27555 Request_Cancelled 1757 Timer_EntityBody 428 Forbidden 247 URL 130 Hostname 117 BadRequest 102 Connection_Dropped 96 Client_Reset 88 Connection_Dropped_List_Full 40 Verb 10 Header 7 Connection_Abandoned_By_ReqQueue 1
Any help is really appreciated to find the reason why we get connection refused when trying to open web site hosted on this server.