Symantec Endpoint Protection (SEP) clients running 14.2 or 14.2 MP1 fail to communicate with the SEP Manager with an HTTP Error 400.
10/11 11:49:36 [3652:5796] ProcessReq >> Bad request, Secreg cannot find tag from request! Secreg cannot continue to process this request! Tag is: Mac=".
10/11 11:49:36 [3652:5796] 4 Bad Request, MacAddress is invalid!
The SEP Manager is expecting a Gateway address from the client. When the SEP client does not have a Gateway address configured within its network adaptor settings this entry is empty and the SEPM rejects it.
This issue is fixed in Symantec Endpoint Protection (SEP) 14.2 RU1. For information on how to obtain the latest build of Symantec Endpoint Protection, see Download the latest version of Symantec software here.
As a workaround, you can manually set a gateway address for the SEP Manager and SEP client.