By default, when you publish Active Directory Federation Services (AD FS) 2.0 servers by using Microsoft Forefront Unified Access Gateway (UAG) 2010, the built-in AD FS template is used. However, in a scenario in which this configuration is loaded with approximately 250 concurrent users, the server that is running Forefront UAG may stop responding or crash with "HTTP 503" errors. The "HTTP 503" errors are returned from Internet Information Services (IIS) because the IIS request queues are full.
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