Connect to the iDRAC IP using an SSH client and login using the username and password of the iDRAC console.
To soft reboot the server the iDRAC is connected to just run the following commands:
/admin1->cd system1 /admin1->reset
If you have issues with the web console being "flaky" then you can also reset this using the following commands:
/admin1/> racadm racadm>>racadm racreset soft
It may take a few minutes for the RAC to come online again.