Do you have a custom certificate for SSL by chance? If this is the case please see the following:
https://github.com/allegroai/clearml/issues/7
The solution would be changing the following to false:
https://github.com/allegroai/clearml/blob/9624f2c715df933ff17ed5ae9bf3c0a0b5fd5a0e/docs/clearml.conf#L16