I have a strange and intermittent problem. I use Forefront TMG 2010 to publish Exchange 2010 (using separate rules for webmail, Active Sync, and Outlook anywhere + autodiscover. Normally this works correctly but we have instances where traffic is being dropped by TMG, but at the very same time, traffic from other networks into the same TMG are working correctly.
So I get a complaint from one user located somewhere that whenever he tries to reach the webmail URL he gets " internet explorer cannot display the page", whilst at the very same time, I am able to access OWA from my home, when using my phone and even from the office. Now if troubleshooting the issue, and using TMG's log I can see that from the IP address at which the complaining users is at, packets are being dropped with messages similar to :
Whilst at the very same time, people from other locations have no problems whatsoever to reach the very same published website. The only fix is to restart the Microsoft Forefront firewall, after the recycle of this service connectivity is restored for the complaining user.