EMS - FortiClient disconnected

Dears, I have EMS 7.2.3 build 0949

First, when integrated with AD for my environment that includes 1700 users, I had many computers showing with no User and no IP for almost 1000 machines.

Should I install forticlient by group policy? I did that but still showed the same, then I connected to each machine and just mentioned EMS IP and connected then all was fine.

Today I found some machines when I add the EMS to connect it gives an error: "the endpoint is blocked from connection to EMS".

Kindly for your advice.