When I deploy the Web Monitor of a Forefornt UAG acting as a DirectAccess gateway trough a Forefront UAG portal I was surprised to saw the error page as below:
After analysing the events on the Forefront UAG Web monitor we could see that it tries to access to unauthorized resources:
n order to apply a workaround, after publishing the Web Monitor go to the Trunk Configuration of the associated trunk:
On the URL Set tab you must have 32 WebMonitor rules, after the last one add these rules with Add Primary :
Then Activate again the Forefront UAG configuration.
And after that, all working fine again.