Getting "!! Submission failed: Grader sent no response".
Going to discussion forums to check what that means and seeing "Your IP address is currently being blocked." on the web page.
Opening from mobile device gives the same result (so it's not device/browser specific).
Disabling wifi and opening page via 4g works (that's how I could Coursera-login to this support forum).
Some technical help from Coursera would be appreciated.
Best answer by Maryam
Please click the Help Center link located on the top right corner of the screen. If there is a blue "live chat" option, try to chat with the agents and report what you are experiencing at the moment.