If its using an smi-s provider, try using the SolarWinds.CIMbrowser to connect.
It should be located in C:\Program Files (x86)\SolarWinds\Orion\SRM
also, try logging into the HMC web interface first (https://ds8xxx-IP) to check which port SMI-S is listening on as it will automatically show up. In our case it is 8452 on DS8884. The standard ports listed for SMI-S are 5989/5988 which are not active.
In our case we still chasing IBM support as the user that was created for monitoring via SRM fails to authenticate even though web browser login works just fine with the same credentials.