In the NTLM Agent configuration you can specify the maximum number of concurrent connections and threads per connection.
I would recommend to have a look at the error logs that MWG produces to see if there is any issue reported related to authentication. For this kind of issue always make sure that you file an SR with support, since a more in-depth analysis is most likely required to find the root cause.
there is a chance that your problem is related to a known issue in MWG 7.1.5. You could proof this by turning off the encryption of the communication between MWG and the Agent temporarily. You need to do this on both ends, MWG (use secure Agent connection) and the Agent (use SSL).
I also had TCP RST ans SSL renogotiation errors. The UI only logs the problem (red dot) after a while to outage can be quite long.
Its worse with intergrated authentication as browsers fails to basic confusing users as they dont enter the realm or are reprompted and lock out account thinking they mistyped.
NTLM-Agents work again after testing in the web interface.
Advised you to to move to NTLM.
We are already using NTLM authentication
The issue was with the TCP connection timeout with the NTLM agent.
This value is hardcoded as 10ms in version 7.1.5 and in version 7.2.0 , this value has been changed to 3s.
Upgrading the version seems to have resolved the issue.