Ongoing STAS Problems - no internet access

Question

I am experiencing ongoing issues with STAS and SSO at 2 different sites running SFOS 17.1.1 MR-1 on Sophos appliances. A number of frustrated users have reported that they lose internet access intermittently throughout the day and I've spent a number of days troubleshooting the problem with Sophos support. 
 STAS was configured on 2 domain controllers as per the official guide below: community.sophos.com/.../123154 
 Settings include: 
 - Workstation Polling Settings as WMI - Enabled Logoff Detection - Detection: Workstation Polling 
 Windows firewalls on Windows servers and workstations have been temporarily disabled for troubleshooting purposes. 
 Based on my last interaction and recommendation by the Sophos support engineer, the "Detection" setting was changed to Ping. It's weekend so will only know tomorrow if this change has made a difference to the behavior of arbitrarily logging off users. 
 In the meantime, I would like to know if anyone else has experienced this behaviour and would appreciate some feedback/advice.

envercpt · Answer

---RESOLVED--- 
 1. On STAS each of the DCs were in different collector groups. Deleted and added one of the DCs to the same collector group as the other. 
 2. On the DCs, changed "Logoff Detection" to Ping. Not sure if this is necessary but since it's working I have not yet reverted to the default settings.