The security token is an automatically generated key that must be added to the end of the password to log in to Salesforce from an untrusted network.Concatenate the password and token when passing the request for authentication.
https://help.salesforce.com/articleView?id=remoteaccess_oauth_username_password_flow.htm&;type=5
All connection troubleshooting, Please try using CURL Utility to connect to Saleforce outside MIMB bridge
the Curl command example:
curl [-v] https://xxx. my.salesforce.com/services/oauth2/token
-d "grant_type=password" -d "client_id=3MVG9_I_oWkIqLrkBt3CnTNCfj9pMzwk.yl0yhgyxmXzL0vSp5yrZcLbRgG1BhNJM4q_gU1c3Nd3cf0L.XByW"
-d "client_secret=<consumer_secret>"
-d "username=xxxx@abcd.com.bkdev" -d "password=<password>"
For information, Please reference Salesforce manual for credential:
