NTLM authentication stops working after a while

Question

I am currently in the process of migrating UTM to XG. I have XG setup and working however it is causing me serious problems with NTLM authentication and the Sophos setup guides are not exactly brilliant because they refer to different versions and solutions. 
 The problem that I have is that NTLM works for about 30 minutes after login and then stops working altogether. The user then has to log out and log back in for web filtering to work correctly. 
 
 Any help appreciated. 
 
 Thanks

Mohammed Islam · Accepted Answer

Hi Aditya, 
 
 I resolved this particular issue, it was due to the fact that I never put in place the DNS request routes for our domain to our internal AD servers. 
 On another note I have to say I have been very disappointed with the level of support/knowledge from Sophos. I have been using an Astaro firewall since V7 and then eventually Sophos UTM. I have never had to call Sophos support and have always relied on the Astaro/Sophos forum for support and individuals like Balfson and Scott Klassen have always provided prompt support so it was never necessary to place a call. Since trying to migrate to Sophos XG I have been on the phone to Sophos multiple times and wasted countless hours only to find the solution myself, which is great because I learn how to fix the issues however I find that very disappointing because Sophos are trying to push XG out to clients via account managers but the support knowledge is not quite there yet. 
 This is not aimed at anyone in the Sophos support community but it would be great if someone could relay this up through the chain of command. 
 
 Thanks, 
 
 Mohammed