Intermittent Port 443 (SSL) on SBS Server 2011

Hi all,

So I've been confounded by a weird problem a client of mine is having.  They have an ADSL connection with a static IP address, a proper SSL certificate (assigned by a trusted authority) and are running SBS 2011.
The firewall has ports 80 and 443 forwarded.
Outlook Web Access and ActiveSync access keep dropping.
We investigated and found port 443 seems to be unavailable about 50% of the time, despite port 80 being available 99% of the time.
Telnet shows the same thing.
We've replaced the modem, the switch, disabled Sharepoint, etc. - anything we though might be interfering with 443 but no dice.
Today I installed CurrPorts to see what is listening on port 443 and found two entries but neither tell me what the process is - is this normal?
I also created a port forwarding entry in the firewall that went from 1443 externally to 443 internally - telnet on this works every time, although trying timed out.
I've attached the currports finding as what concerned me was the lack of info of any kind about the process listening.

Any ideas?

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Chris HInfrastructure ManagerCommented:
Are you saying even on the LAN, internally from server:443 to server:443, you're having intermittent connectivity issues?  Or only with WAN/internet outside of your network?
Mango-ManAuthor Commented:
Only from the WAN side - internally is fine.  I'm thinking it may be a problem with the ISP, upstream even from the ADSL modem.
David AtkinTechnical DirectorCommented:
What router are you using?

Do you have any other website on the SBS?

Check your IIS logs located here for anything obvious:


Does curtports show which PID's are listening? If so you can work out which processes based on that by using Task Manager

If it works internally 100% of the time it sounds more like a firewall/router issue
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Mango-ManAuthor Commented:
Hi David,

Yep agree but we've replaced the router (they are using their ADSL modem - yes I know, we've tried getting them on a Fortinet).  This same arrangement works for other customers and the modem has been replaced with a different model.  We've checked and re-created the virtual servers over and over.  As per the attachment, the process ID is 4 which is 'SYSTEM' which isn't particularly helpful!
David AtkinTechnical DirectorCommented:
Which particular ADSL modem/router  are you using?
Chris HInfrastructure ManagerCommented:
When you say you can't connect, does it just disappear, or is there any associated browser error with it?  Is you time set correctly?  Can you validate you're not using some shady NTP server or a local NTP server or Vmware host isn't changing the system time back and forth with your domain controller(s)?

How have you verified failed connectivity?  Just browser timeouts?

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Mango-ManAuthor Commented:
Apologies all for the tardy response - I completely forgot about this.  So we replaced the modem again and voila, problem solved.

3 ADSL modems and only one worked - what are the chances?
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